diff --git a/src/IdentityAuthClient.tsx b/src/IdentityAuthClient.tsx
index 12f42a3add1..4df9959511f 100644
--- a/src/IdentityAuthClient.tsx
+++ b/src/IdentityAuthClient.tsx
@@ -118,7 +118,7 @@ export default class IdentityAuthClient {
     }
 
     private async checkToken(token: string): Promise<void> {
-        const identityServerUrl = this.matrixClient.getIdentityServerUrl();
+        const identityServerUrl = this.matrixClient.getIdentityServerUrl()!;
 
         try {
             await this.matrixClient.getIdentityAccount(token);
diff --git a/src/LegacyCallHandler.tsx b/src/LegacyCallHandler.tsx
index f84509238b7..71891a3e130 100644
--- a/src/LegacyCallHandler.tsx
+++ b/src/LegacyCallHandler.tsx
@@ -579,7 +579,7 @@ export default class LegacyCallHandler extends EventEmitter {
             });
         });
         call.on(CallEvent.Hangup, () => {
-            if (!this.matchesCallForThisRoom(call)) return;
+            if (!mappedRoomId || !this.matchesCallForThisRoom(call)) return;
 
             this.removeCallForRoom(mappedRoomId);
         });
@@ -587,7 +587,7 @@ export default class LegacyCallHandler extends EventEmitter {
             this.onCallStateChanged(newState, oldState, call);
         });
         call.on(CallEvent.Replaced, (newCall: MatrixCall) => {
-            if (!this.matchesCallForThisRoom(call)) return;
+            if (!mappedRoomId || !this.matchesCallForThisRoom(call)) return;
 
             logger.log(`Call ID ${call.callId} is being replaced by call ID ${newCall.callId}`);
 
@@ -603,7 +603,7 @@ export default class LegacyCallHandler extends EventEmitter {
             this.setCallState(newCall, newCall.state);
         });
         call.on(CallEvent.AssertedIdentityChanged, async (): Promise<void> => {
-            if (!this.matchesCallForThisRoom(call)) return;
+            if (!mappedRoomId || !this.matchesCallForThisRoom(call)) return;
 
             logger.log(`Call ID ${call.callId} got new asserted identity:`, call.getRemoteAssertedIdentity());
 
@@ -634,7 +634,7 @@ export default class LegacyCallHandler extends EventEmitter {
 
                 const newMappedRoomId = this.roomIdForCall(call);
                 logger.log(`Old room ID: ${mappedRoomId}, new room ID: ${newMappedRoomId}`);
-                if (newMappedRoomId !== mappedRoomId) {
+                if (newMappedRoomId && newMappedRoomId !== mappedRoomId) {
                     this.removeCallForRoom(mappedRoomId);
                     mappedRoomId = newMappedRoomId;
                     logger.log("Moving call to room " + mappedRoomId);
@@ -1116,6 +1116,14 @@ export default class LegacyCallHandler extends EventEmitter {
     public async startTransferToMatrixID(call: MatrixCall, destination: string, consultFirst: boolean): Promise<void> {
         if (consultFirst) {
             const dmRoomId = await ensureDMExists(MatrixClientPeg.get(), destination);
+            if (!dmRoomId) {
+                logger.log("Failed to transfer call, could not ensure dm exists");
+                Modal.createDialog(ErrorDialog, {
+                    title: _t("Transfer Failed"),
+                    description: _t("Failed to transfer call"),
+                });
+                return;
+            }
 
             this.placeCall(dmRoomId, call.type, call);
             dis.dispatch<ViewRoomPayload>({
diff --git a/src/Lifecycle.ts b/src/Lifecycle.ts
index 6c2fbec8219..3c679c8a6d8 100644
--- a/src/Lifecycle.ts
+++ b/src/Lifecycle.ts
@@ -176,7 +176,7 @@ export async function loadSession(opts: ILoadSessionOpts = {}): Promise<boolean>
  */
 export async function getStoredSessionOwner(): Promise<[string, boolean] | [null, null]> {
     const { hsUrl, userId, hasAccessToken, isGuest } = await getStoredSessionVars();
-    return hsUrl && userId && hasAccessToken ? [userId, isGuest] : [null, null];
+    return hsUrl && userId && hasAccessToken ? [userId, !!isGuest] : [null, null];
 }
 
 /**
@@ -343,9 +343,9 @@ export interface IStoredSession {
  * may not be valid, as it is not tested for consistency here.
  * @returns {Object} Information about the session - see implementation for variables.
  */
-export async function getStoredSessionVars(): Promise<IStoredSession> {
-    const hsUrl = localStorage.getItem(HOMESERVER_URL_KEY);
-    const isUrl = localStorage.getItem(ID_SERVER_URL_KEY);
+export async function getStoredSessionVars(): Promise<Partial<IStoredSession>> {
+    const hsUrl = localStorage.getItem(HOMESERVER_URL_KEY) ?? undefined;
+    const isUrl = localStorage.getItem(ID_SERVER_URL_KEY) ?? undefined;
     let accessToken: string | undefined;
     try {
         accessToken = await StorageManager.idbLoad("account", "mx_access_token");
@@ -367,8 +367,8 @@ export async function getStoredSessionVars(): Promise<IStoredSession> {
     // if we pre-date storing "mx_has_access_token", but we retrieved an access
     // token, then we should say we have an access token
     const hasAccessToken = localStorage.getItem("mx_has_access_token") === "true" || !!accessToken;
-    const userId = localStorage.getItem("mx_user_id");
-    const deviceId = localStorage.getItem("mx_device_id");
+    const userId = localStorage.getItem("mx_user_id") ?? undefined;
+    const deviceId = localStorage.getItem("mx_device_id") ?? undefined;
 
     let isGuest: boolean;
     if (localStorage.getItem("mx_is_guest") !== null) {
@@ -447,7 +447,7 @@ export async function restoreFromLocalStorage(opts?: { ignoreGuest?: boolean }):
         }
 
         let decryptedAccessToken = accessToken;
-        const pickleKey = await PlatformPeg.get()?.getPickleKey(userId, deviceId);
+        const pickleKey = await PlatformPeg.get()?.getPickleKey(userId, deviceId ?? "");
         if (pickleKey) {
             logger.log("Got pickle key");
             if (typeof accessToken !== "string") {
@@ -740,7 +740,7 @@ export function logout(): void {
 
     _isLoggingOut = true;
     const client = MatrixClientPeg.get();
-    PlatformPeg.get()?.destroyPickleKey(client.getSafeUserId(), client.getDeviceId());
+    PlatformPeg.get()?.destroyPickleKey(client.getSafeUserId(), client.getDeviceId() ?? "");
     client.logout(true).then(onLoggedOut, (err) => {
         // Just throwing an error here is going to be very unhelpful
         // if you're trying to log out because your server's down and
diff --git a/src/ScalarAuthClient.ts b/src/ScalarAuthClient.ts
index 558e6362b9f..5a57729e53b 100644
--- a/src/ScalarAuthClient.ts
+++ b/src/ScalarAuthClient.ts
@@ -50,7 +50,7 @@ export default class ScalarAuthClient {
     }
 
     private writeTokenToStore(): void {
-        window.localStorage.setItem("mx_scalar_token_at_" + this.apiUrl, this.scalarToken);
+        window.localStorage.setItem("mx_scalar_token_at_" + this.apiUrl, this.scalarToken ?? "");
         if (this.isDefaultManager) {
             // We remove the old token from storage to migrate upwards. This is safe
             // to do because even if the user switches to /app when this is on /develop
@@ -260,7 +260,7 @@ export default class ScalarAuthClient {
         const roomId = room.roomId;
         const roomName = room.name;
         let url = this.uiUrl;
-        url += "?scalar_token=" + encodeURIComponent(this.scalarToken);
+        if (this.scalarToken) url += "?scalar_token=" + encodeURIComponent(this.scalarToken);
         url += "&room_id=" + encodeURIComponent(roomId);
         url += "&room_name=" + encodeURIComponent(roomName);
         url += "&theme=" + encodeURIComponent(SettingsStore.getValue("theme"));
@@ -274,6 +274,7 @@ export default class ScalarAuthClient {
     }
 
     public getStarterLink(starterLinkUrl: string): string {
+        if (!this.scalarToken) return starterLinkUrl;
         return starterLinkUrl + "?scalar_token=" + encodeURIComponent(this.scalarToken);
     }
 }
diff --git a/src/components/views/auth/CountryDropdown.tsx b/src/components/views/auth/CountryDropdown.tsx
index a9061f6e5af..dc8ff2e1a3c 100644
--- a/src/components/views/auth/CountryDropdown.tsx
+++ b/src/components/views/auth/CountryDropdown.tsx
@@ -69,7 +69,7 @@ export default class CountryDropdown extends React.Component<IProps, IState> {
                 const locale = new Intl.Locale(navigator.language ?? navigator.languages[0]);
                 const code = locale.region ?? locale.language ?? locale.baseName;
                 const displayNames = new Intl.DisplayNames(["en"], { type: "region" });
-                const displayName = displayNames.of(code).toUpperCase();
+                const displayName = displayNames.of(code)?.toUpperCase();
                 defaultCountry = COUNTRIES.find(
                     (c) => c.iso2 === code.toUpperCase() || c.name.toUpperCase() === displayName,
                 );
diff --git a/src/components/views/dialogs/ServerPickerDialog.tsx b/src/components/views/dialogs/ServerPickerDialog.tsx
index 2b208b29f3f..d7469b86946 100644
--- a/src/components/views/dialogs/ServerPickerDialog.tsx
+++ b/src/components/views/dialogs/ServerPickerDialog.tsx
@@ -49,7 +49,7 @@ export default class ServerPickerDialog extends React.PureComponent<IProps, ISta
         super(props);
 
         const config = SdkConfig.get();
-        this.defaultServer = config["validated_server_config"];
+        this.defaultServer = config["validated_server_config"]!;
         const { serverConfig } = this.props;
 
         let otherHomeserver = "";
@@ -152,11 +152,11 @@ export default class ServerPickerDialog extends React.PureComponent<IProps, ISta
     private onSubmit = async (ev: SyntheticEvent): Promise<void> => {
         ev.preventDefault();
 
-        const valid = await this.fieldRef.current.validate({ allowEmpty: false });
+        const valid = await this.fieldRef.current?.validate({ allowEmpty: false });
 
         if (!valid && !this.state.defaultChosen) {
-            this.fieldRef.current.focus();
-            this.fieldRef.current.validate({ allowEmpty: false, focused: true });
+            this.fieldRef.current?.focus();
+            this.fieldRef.current?.validate({ allowEmpty: false, focused: true });
             return;
         }
 
diff --git a/src/components/views/dialogs/spotlight/SpotlightDialog.tsx b/src/components/views/dialogs/spotlight/SpotlightDialog.tsx
index 05ab8c1749a..2939d7f46d1 100644
--- a/src/components/views/dialogs/spotlight/SpotlightDialog.tsx
+++ b/src/components/views/dialogs/spotlight/SpotlightDialog.tsx
@@ -1089,7 +1089,7 @@ const SpotlightDialog: React.FC<IProps> = ({ initialText = "", initialFilter = n
                 ev.stopPropagation();
                 ev.preventDefault();
 
-                if (rovingContext.state.refs.length > 0) {
+                if (rovingContext.state.activeRef && rovingContext.state.refs.length > 0) {
                     let refs = rovingContext.state.refs;
                     if (!query && !filter !== null) {
                         // If the current selection is not in the recently viewed row then only include the
@@ -1112,6 +1112,7 @@ const SpotlightDialog: React.FC<IProps> = ({ initialText = "", initialFilter = n
                 if (
                     !query &&
                     !filter !== null &&
+                    rovingContext.state.activeRef &&
                     rovingContext.state.refs.length > 0 &&
                     refIsForRecentlyViewed(rovingContext.state.activeRef)
                 ) {
diff --git a/src/components/views/elements/CopyableText.tsx b/src/components/views/elements/CopyableText.tsx
index e1783013cb8..36da6cb4a21 100644
--- a/src/components/views/elements/CopyableText.tsx
+++ b/src/components/views/elements/CopyableText.tsx
@@ -25,7 +25,7 @@ import AccessibleTooltipButton from "./AccessibleTooltipButton";
 
 interface IProps {
     children?: React.ReactNode;
-    getTextToCopy: () => string;
+    getTextToCopy: () => string | null;
     border?: boolean;
     className?: string;
 }
@@ -35,7 +35,8 @@ const CopyableText: React.FC<IProps> = ({ children, getTextToCopy, border = true
 
     const onCopyClickInternal = async (e: ButtonEvent): Promise<void> => {
         e.preventDefault();
-        const successful = await copyPlaintext(getTextToCopy());
+        const text = getTextToCopy();
+        const successful = !!text && (await copyPlaintext(text));
         setTooltip(successful ? _t("Copied!") : _t("Failed to copy"));
     };
 
diff --git a/src/components/views/emojipicker/EmojiPicker.tsx b/src/components/views/emojipicker/EmojiPicker.tsx
index 7a62c4dd079..45464a2a74f 100644
--- a/src/components/views/emojipicker/EmojiPicker.tsx
+++ b/src/components/views/emojipicker/EmojiPicker.tsx
@@ -162,9 +162,9 @@ class EmojiPicker extends React.Component<IProps, IState> {
     };
 
     private keyboardNavigation(ev: React.KeyboardEvent, state: RovingState, dispatch: Dispatch<RovingAction>): void {
-        const node = state.activeRef.current;
-        const parent = node.parentElement;
-        if (!parent) return;
+        const node = state.activeRef?.current;
+        const parent = node?.parentElement;
+        if (!parent || !state.activeRef) return;
         const rowIndex = Array.from(parent.children).indexOf(node);
         const refIndex = state.refs.indexOf(state.activeRef);
 
@@ -173,12 +173,12 @@ class EmojiPicker extends React.Component<IProps, IState> {
         switch (ev.key) {
             case Key.ARROW_LEFT:
                 focusRef = state.refs[refIndex - 1];
-                newParent = focusRef?.current?.parentElement;
+                newParent = focusRef?.current?.parentElement ?? undefined;
                 break;
 
             case Key.ARROW_RIGHT:
                 focusRef = state.refs[refIndex + 1];
-                newParent = focusRef?.current?.parentElement;
+                newParent = focusRef?.current?.parentElement ?? undefined;
                 break;
 
             case Key.ARROW_UP:
@@ -188,7 +188,7 @@ class EmojiPicker extends React.Component<IProps, IState> {
                     ev.key === Key.ARROW_UP
                         ? state.refs[refIndex - rowIndex - 1]
                         : state.refs[refIndex - rowIndex + EMOJIS_PER_ROW];
-                newParent = ref?.current?.parentElement;
+                newParent = ref?.current?.parentElement ?? undefined;
                 const newTarget = newParent?.children[clamp(rowIndex, 0, newParent.children.length - 1)];
                 focusRef = state.refs.find((r) => r.current === newTarget);
                 break;
diff --git a/src/components/views/rooms/EditMessageComposer.tsx b/src/components/views/rooms/EditMessageComposer.tsx
index 96c66dddfb6..c1fdecdd475 100644
--- a/src/components/views/rooms/EditMessageComposer.tsx
+++ b/src/components/views/rooms/EditMessageComposer.tsx
@@ -386,8 +386,8 @@ class EditMessageComposer extends React.Component<IEditMessageComposerProps, ISt
         // in case we're currently editing a pending event
         const sel = document.getSelection()!;
         let caret: DocumentOffset | undefined;
-        if (sel.focusNode) {
-            caret = getCaretOffsetAndText(this.editorRef.current?.editorRef.current, sel).caret;
+        if (sel.focusNode && this.editorRef.current?.editorRef.current) {
+            caret = getCaretOffsetAndText(this.editorRef.current.editorRef.current, sel).caret;
         }
         const parts = this.model.serializeParts();
         // if caret is undefined because for some reason there isn't a valid selection,
@@ -458,12 +458,15 @@ class EditMessageComposer extends React.Component<IEditMessageComposerProps, ISt
     };
 
     public render(): React.ReactNode {
+        const room = this.getRoom();
+        if (!room) return null;
+
         return (
             <div className={classNames("mx_EditMessageComposer", this.props.className)} onKeyDown={this.onKeyDown}>
                 <BasicMessageComposer
                     ref={this.editorRef}
                     model={this.model}
-                    room={this.getRoom()}
+                    room={room}
                     threadId={this.props.editState?.getEvent()?.getThread()?.id}
                     initialCaret={this.props.editState.getCaret() ?? undefined}
                     label={_t("Edit message")}
diff --git a/src/components/views/rooms/RoomList.tsx b/src/components/views/rooms/RoomList.tsx
index 98a3260b666..921c1e24677 100644
--- a/src/components/views/rooms/RoomList.tsx
+++ b/src/components/views/rooms/RoomList.tsx
@@ -16,7 +16,7 @@ limitations under the License.
 
 import { EventType, RoomType } from "matrix-js-sdk/src/@types/event";
 import { Room } from "matrix-js-sdk/src/models/room";
-import React, { ComponentType, createRef, ReactComponentElement, RefObject, SyntheticEvent } from "react";
+import React, { ComponentType, createRef, ReactComponentElement, SyntheticEvent } from "react";
 
 import { IState as IRovingTabIndexState, RovingTabIndexProvider } from "../../../accessibility/RovingTabIndex";
 import MatrixClientContext from "../../../contexts/MatrixClientContext";
@@ -106,8 +106,8 @@ type TagAestheticsMap = Partial<{
     [tagId in TagID]: ITagAesthetics;
 }>;
 
-const auxButtonContextMenuPosition = (handle: RefObject<HTMLDivElement>): MenuProps => {
-    const rect = handle.current.getBoundingClientRect();
+const auxButtonContextMenuPosition = (handle: HTMLDivElement): MenuProps => {
+    const rect = handle.getBoundingClientRect();
     return {
         chevronFace: ChevronFace.None,
         left: rect.left - 7,
@@ -126,11 +126,11 @@ const DmAuxButton: React.FC<IAuxButtonProps> = ({ tabIndex, dispatcher = default
 
     if (activeSpace && (showCreateRooms || showInviteUsers)) {
         let contextMenu: JSX.Element | undefined;
-        if (menuDisplayed) {
+        if (menuDisplayed && handle.current) {
             const canInvite = shouldShowSpaceInvite(activeSpace);
 
             contextMenu = (
-                <IconizedContextMenu {...auxButtonContextMenuPosition(handle)} onFinished={closeMenu} compact>
+                <IconizedContextMenu {...auxButtonContextMenuPosition(handle.current)} onFinished={closeMenu} compact>
                     <IconizedContextMenuOptionList first>
                         {showCreateRooms && (
                             <IconizedContextMenuOption
@@ -357,9 +357,9 @@ const UntaggedAuxButton: React.FC<IAuxButtonProps> = ({ tabIndex }) => {
     }
 
     let contextMenu: JSX.Element | null = null;
-    if (menuDisplayed) {
+    if (menuDisplayed && handle.current) {
         contextMenu = (
-            <IconizedContextMenu {...auxButtonContextMenuPosition(handle)} onFinished={closeMenu} compact>
+            <IconizedContextMenu {...auxButtonContextMenuPosition(handle.current)} onFinished={closeMenu} compact>
                 {contextMenuContent}
             </IconizedContextMenu>
         );
@@ -491,6 +491,7 @@ export default class RoomList extends React.PureComponent<IProps, IState> {
         if (payload.action === Action.ViewRoomDelta) {
             const viewRoomDeltaPayload = payload as ViewRoomDeltaPayload;
             const currentRoomId = SdkContextClass.instance.roomViewStore.getRoomId();
+            if (!currentRoomId) return;
             const room = this.getRoomDelta(currentRoomId, viewRoomDeltaPayload.delta, viewRoomDeltaPayload.unread);
             if (room) {
                 defaultDispatcher.dispatch<ViewRoomPayload>({
diff --git a/src/components/views/rooms/RoomTile.tsx b/src/components/views/rooms/RoomTile.tsx
index 87166c94a19..58664951df0 100644
--- a/src/components/views/rooms/RoomTile.tsx
+++ b/src/components/views/rooms/RoomTile.tsx
@@ -207,7 +207,8 @@ export class RoomTile extends React.PureComponent<ClassProps, State> {
             return;
         }
 
-        const messagePreview = await MessagePreviewStore.instance.getPreviewForRoom(this.props.room, this.props.tag);
+        const messagePreview =
+            (await MessagePreviewStore.instance.getPreviewForRoom(this.props.room, this.props.tag)) ?? undefined;
         this.setState({ messagePreview });
     }
 
diff --git a/src/components/views/rooms/wysiwyg_composer/hooks/usePlainTextListeners.ts b/src/components/views/rooms/wysiwyg_composer/hooks/usePlainTextListeners.ts
index f8b045ad657..f918ceb50df 100644
--- a/src/components/views/rooms/wysiwyg_composer/hooks/usePlainTextListeners.ts
+++ b/src/components/views/rooms/wysiwyg_composer/hooks/usePlainTextListeners.ts
@@ -38,7 +38,7 @@ export function usePlainTextListeners(
     onChange?: (content: string) => void,
     onSend?: () => void,
 ): {
-    ref: RefObject<HTMLDivElement | null>;
+    ref: RefObject<HTMLDivElement>;
     content?: string;
     onInput(event: SyntheticEvent<HTMLDivElement, InputEvent | ClipboardEvent>): void;
     onPaste(event: SyntheticEvent<HTMLDivElement, InputEvent | ClipboardEvent>): void;
diff --git a/src/components/views/settings/SecureBackupPanel.tsx b/src/components/views/settings/SecureBackupPanel.tsx
index 2b19a8af583..da67d6a919e 100644
--- a/src/components/views/settings/SecureBackupPanel.tsx
+++ b/src/components/views/settings/SecureBackupPanel.tsx
@@ -295,7 +295,7 @@ export default class SecureBackupPanel extends React.PureComponent<{}, IState> {
                 const verify = (sub: string): JSX.Element => (
                     <span
                         className={
-                            sig.device && sig.deviceTrust.isVerified()
+                            sig.device && sig.deviceTrust?.isVerified()
                                 ? "mx_SecureBackupPanel_deviceVerified"
                                 : "mx_SecureBackupPanel_deviceNotVerified"
                         }
@@ -347,7 +347,7 @@ export default class SecureBackupPanel extends React.PureComponent<{}, IState> {
                         {},
                         { validity },
                     );
-                } else if (sig.valid && sig.deviceTrust.isVerified()) {
+                } else if (sig.valid && sig.deviceTrust?.isVerified()) {
                     sigStatus = _t(
                         "Backup has a <validity>valid</validity> signature from " +
                             "<verify>verified</verify> session <device></device>",
@@ -361,7 +361,7 @@ export default class SecureBackupPanel extends React.PureComponent<{}, IState> {
                         {},
                         { validity, verify, device },
                     );
-                } else if (!sig.valid && sig.deviceTrust.isVerified()) {
+                } else if (!sig.valid && sig.deviceTrust?.isVerified()) {
                     sigStatus = _t(
                         "Backup has an <validity>invalid</validity> signature from " +
                             "<verify>verified</verify> session <device></device>",
diff --git a/src/components/views/settings/tabs/user/LabsUserSettingsTab.tsx b/src/components/views/settings/tabs/user/LabsUserSettingsTab.tsx
index 498aaf03317..f505ebb76f9 100644
--- a/src/components/views/settings/tabs/user/LabsUserSettingsTab.tsx
+++ b/src/components/views/settings/tabs/user/LabsUserSettingsTab.tsx
@@ -67,7 +67,7 @@ export default class LabsUserSettingsTab extends React.Component<{}> {
             const groups = new EnhancedMap<LabGroup, JSX.Element[]>();
             this.labs.forEach((f) => {
                 groups
-                    .getOrCreate(SettingsStore.getLabGroup(f), [])
+                    .getOrCreate(SettingsStore.getLabGroup(f)!, [])
                     .push(<SettingsFlag level={SettingLevel.DEVICE} name={f} key={f} />);
             });
 
diff --git a/src/components/views/spaces/QuickSettingsButton.tsx b/src/components/views/spaces/QuickSettingsButton.tsx
index 4f9529466b0..458dcaeac49 100644
--- a/src/components/views/spaces/QuickSettingsButton.tsx
+++ b/src/components/views/spaces/QuickSettingsButton.tsx
@@ -68,14 +68,14 @@ const QuickSettingsButton: React.FC<{
                     {_t("All settings")}
                 </AccessibleButton>
 
-                {SettingsStore.getValue("developerMode") && (
+                {SettingsStore.getValue("developerMode") && SdkContextClass.instance.roomViewStore.getRoomId() && (
                     <AccessibleButton
                         onClick={() => {
                             closeMenu();
                             Modal.createDialog(
                                 DevtoolsDialog,
                                 {
-                                    roomId: SdkContextClass.instance.roomViewStore.getRoomId(),
+                                    roomId: SdkContextClass.instance.roomViewStore.getRoomId()!,
                                 },
                                 "mx_DevtoolsDialog_wrapper",
                             );
diff --git a/src/components/views/spaces/SpaceTreeLevel.tsx b/src/components/views/spaces/SpaceTreeLevel.tsx
index a2f8719add0..1d31e9d141f 100644
--- a/src/components/views/spaces/SpaceTreeLevel.tsx
+++ b/src/components/views/spaces/SpaceTreeLevel.tsx
@@ -122,7 +122,7 @@ export const SpaceButton = forwardRef<HTMLElement, IButtonProps>(
         }
 
         let contextMenu: JSX.Element | undefined;
-        if (menuDisplayed && handle.current && ContextMenuComponent) {
+        if (space && menuDisplayed && handle.current && ContextMenuComponent) {
             contextMenu = (
                 <ContextMenuComponent
                     {...toRightOf(handle.current.getBoundingClientRect(), 0)}
diff --git a/src/components/views/toasts/VerificationRequestToast.tsx b/src/components/views/toasts/VerificationRequestToast.tsx
index 70c85ab6748..8f27905bce7 100644
--- a/src/components/views/toasts/VerificationRequestToast.tsx
+++ b/src/components/views/toasts/VerificationRequestToast.tsx
@@ -74,10 +74,12 @@ export default class VerificationRequestToast extends React.PureComponent<IProps
 
         if (request.isSelfVerification) {
             const cli = MatrixClientPeg.get();
-            const device = await cli.getDevice(request.channel.deviceId);
-            const ip = device.last_seen_ip;
+            const device = request.channel.deviceId ? await cli.getDevice(request.channel.deviceId) : null;
+            const ip = device?.last_seen_ip;
             this.setState({
-                device: cli.getStoredDevice(cli.getUserId()!, request.channel.deviceId) ?? undefined,
+                device:
+                    (request.channel.deviceId && cli.getStoredDevice(cli.getSafeUserId(), request.channel.deviceId)) ||
+                    undefined,
                 ip,
             });
         }
diff --git a/src/customisations/Security.ts b/src/customisations/Security.ts
index bfc2caadddd..2d83a564f13 100644
--- a/src/customisations/Security.ts
+++ b/src/customisations/Security.ts
@@ -42,7 +42,10 @@ function getSecretStorageKey(): Uint8Array | null {
 }
 
 /* eslint-disable-next-line @typescript-eslint/no-unused-vars */
-function getDehydrationKey(keyInfo: ISecretStorageKeyInfo): Promise<Uint8Array | null> {
+function getDehydrationKey(
+    keyInfo: ISecretStorageKeyInfo,
+    checkFunc: (key: Uint8Array) => void,
+): Promise<Uint8Array | null> {
     return Promise.resolve(null);
 }
 
diff --git a/src/integrations/IntegrationManagers.ts b/src/integrations/IntegrationManagers.ts
index 9adcb561623..da1bb62ba98 100644
--- a/src/integrations/IntegrationManagers.ts
+++ b/src/integrations/IntegrationManagers.ts
@@ -153,7 +153,7 @@ export class IntegrationManagers {
 
             if (kind === Kind.Account) {
                 // Order by state_keys (IDs)
-                managers.sort((a, b) => compare(a.id, b.id));
+                managers.sort((a, b) => compare(a.id ?? "", b.id ?? ""));
             }
 
             ordered.push(...managers);
@@ -199,7 +199,7 @@ export class IntegrationManagers {
         logger.log("Looking up integration manager via .well-known");
         if (domainName.startsWith("http:") || domainName.startsWith("https:")) {
             // trim off the scheme and just use the domain
-            domainName = url.parse(domainName).host;
+            domainName = url.parse(domainName).host!;
         }
 
         let wkConfig: IClientWellKnown;
diff --git a/src/linkify-matrix.ts b/src/linkify-matrix.ts
index 3369a18157b..6f921469c76 100644
--- a/src/linkify-matrix.ts
+++ b/src/linkify-matrix.ts
@@ -16,7 +16,7 @@ limitations under the License.
 */
 
 import * as linkifyjs from "linkifyjs";
-import { Opts, registerCustomProtocol, registerPlugin } from "linkifyjs";
+import { EventListeners, Opts, registerCustomProtocol, registerPlugin } from "linkifyjs";
 import linkifyElement from "linkify-element";
 import linkifyString from "linkify-string";
 import { User } from "matrix-js-sdk/src/matrix";
@@ -136,7 +136,7 @@ export const ELEMENT_URL_PATTERN =
     ")(#.*)";
 
 export const options: Opts = {
-    events: function (href: string, type: string): Partial<GlobalEventHandlers> {
+    events: function (href: string, type: string): EventListeners {
         switch (type as Type) {
             case Type.URL: {
                 // intercept local permalinks to users and show them like userids (in userinfo of current room)
@@ -185,9 +185,11 @@ export const options: Opts = {
                     },
                 };
         }
+
+        return {};
     },
 
-    formatHref: function (href: string, type: Type | string): string {
+    formatHref: function (href: string, type: Type | string): string | null {
         switch (type) {
             case Type.RoomAlias:
             case Type.UserId:
@@ -205,7 +207,7 @@ export const options: Opts = {
 
     className: "linkified",
 
-    target: function (href: string, type: Type | string): string {
+    target: function (href: string, type: Type | string): string | null {
         if (type === Type.URL) {
             try {
                 const transformed = tryTransformPermalinkToLocalHref(href);
diff --git a/src/stores/RoomViewStore.tsx b/src/stores/RoomViewStore.tsx
index dd87a97a57e..7713e3f005a 100644
--- a/src/stores/RoomViewStore.tsx
+++ b/src/stores/RoomViewStore.tsx
@@ -228,6 +228,7 @@ export class RoomViewStore extends EventEmitter {
     }
 
     private doMaybeSetCurrentVoiceBroadcastPlayback(room: Room): void {
+        if (!this.stores.client) return;
         doMaybeSetCurrentVoiceBroadcastPlayback(
             room,
             this.stores.client,
@@ -532,8 +533,8 @@ export class RoomViewStore extends EventEmitter {
 
         const cli = MatrixClientPeg.get();
         // take a copy of roomAlias & roomId as they may change by the time the join is complete
-        const { roomAlias, roomId } = this.state;
-        const address = roomAlias || roomId;
+        const { roomAlias, roomId = payload.roomId } = this.state;
+        const address = roomAlias || roomId!;
         const viaServers = this.state.viaServers || [];
         try {
             await retry<Room, MatrixError>(
@@ -554,7 +555,7 @@ export class RoomViewStore extends EventEmitter {
             // room.
             this.dis.dispatch<JoinRoomReadyPayload>({
                 action: Action.JoinRoomReady,
-                roomId,
+                roomId: roomId!,
                 metricsTrigger: payload.metricsTrigger,
             });
         } catch (err) {
diff --git a/src/stores/ThreepidInviteStore.ts b/src/stores/ThreepidInviteStore.ts
index 6dfb7d05610..c62974378f1 100644
--- a/src/stores/ThreepidInviteStore.ts
+++ b/src/stores/ThreepidInviteStore.ts
@@ -83,7 +83,11 @@ export default class ThreepidInviteStore extends EventEmitter {
         for (let i = 0; i < localStorage.length; i++) {
             const keyName = localStorage.key(i);
             if (!keyName?.startsWith(STORAGE_PREFIX)) continue;
-            results.push(JSON.parse(localStorage.getItem(keyName)) as IPersistedThreepidInvite);
+            try {
+                results.push(JSON.parse(localStorage.getItem(keyName)!) as IPersistedThreepidInvite);
+            } catch (e) {
+                console.warn("Failed to parse 3pid invite", e);
+            }
         }
         return results;
     }
diff --git a/src/stores/spaces/SpaceStore.ts b/src/stores/spaces/SpaceStore.ts
index 4251826f81c..73ec56556d7 100644
--- a/src/stores/spaces/SpaceStore.ts
+++ b/src/stores/spaces/SpaceStore.ts
@@ -144,7 +144,7 @@ export class SpaceStoreClass extends AsyncStoreWithClient<IState> {
     private _activeSpace: SpaceKey = MetaSpace.Home; // set properly by onReady
     private _suggestedRooms: ISuggestedRoom[] = [];
     private _invitedSpaces = new Set<Room>();
-    private spaceOrderLocalEchoMap = new Map<string, string>();
+    private spaceOrderLocalEchoMap = new Map<string, string | undefined>();
     // The following properties are set by onReady as they live in account_data
     private _allRoomsInHome = false;
     private _enabledMetaSpaces: MetaSpace[] = [];
@@ -338,7 +338,7 @@ export class SpaceStoreClass extends AsyncStoreWithClient<IState> {
     };
 
     public addRoomToSpace(space: Room, roomId: string, via: string[], suggested = false): Promise<ISendEventResponse> {
-        return this.matrixClient.sendStateEvent(
+        return this.matrixClient!.sendStateEvent(
             space.roomId,
             EventType.SpaceChild,
             {
@@ -359,7 +359,7 @@ export class SpaceStoreClass extends AsyncStoreWithClient<IState> {
                 return getChildOrder(ev.getContent().order, ev.getTs(), ev.getStateKey()!);
             })
                 .map((ev) => {
-                    const history = this.matrixClient.getRoomUpgradeHistory(
+                    const history = this.matrixClient!.getRoomUpgradeHistory(
                         ev.getStateKey()!,
                         true,
                         this._msc3946ProcessDynamicPredecessor,
@@ -463,7 +463,7 @@ export class SpaceStoreClass extends AsyncStoreWithClient<IState> {
     ): Set<string> => {
         if (space === MetaSpace.Home && this.allRoomsInHome) {
             return new Set(
-                this.matrixClient.getVisibleRooms(this._msc3946ProcessDynamicPredecessor).map((r) => r.roomId),
+                this.matrixClient!.getVisibleRooms(this._msc3946ProcessDynamicPredecessor).map((r) => r.roomId),
             );
         }
 
@@ -612,8 +612,7 @@ export class SpaceStoreClass extends AsyncStoreWithClient<IState> {
             this.roomIdsBySpace.delete(MetaSpace.Home);
         } else {
             const rooms = new Set(
-                this.matrixClient
-                    .getVisibleRooms(this._msc3946ProcessDynamicPredecessor)
+                this.matrixClient!.getVisibleRooms(this._msc3946ProcessDynamicPredecessor)
                     .filter(this.showInHomeSpace)
                     .map((r) => r.roomId),
             );
@@ -813,9 +812,11 @@ export class SpaceStoreClass extends AsyncStoreWithClient<IState> {
                 // Expand room IDs to all known versions of the given rooms
                 const expandedRoomIds = new Set(
                     Array.from(roomIds).flatMap((roomId) => {
-                        return this.matrixClient
-                            .getRoomUpgradeHistory(roomId, true, this._msc3946ProcessDynamicPredecessor)
-                            .map((r) => r.roomId);
+                        return this.matrixClient!.getRoomUpgradeHistory(
+                            roomId,
+                            true,
+                            this._msc3946ProcessDynamicPredecessor,
+                        ).map((r) => r.roomId);
                     }),
                 );
 
@@ -1217,7 +1218,7 @@ export class SpaceStoreClass extends AsyncStoreWithClient<IState> {
                 // Persist last viewed room from a space
                 // we don't await setActiveSpace above as we only care about this.activeSpace being up to date
                 // synchronously for the below code - everything else can and should be async.
-                window.localStorage.setItem(getSpaceContextKey(this.activeSpace), payload.room_id);
+                window.localStorage.setItem(getSpaceContextKey(this.activeSpace), payload.room_id ?? "");
                 break;
             }
 
@@ -1294,10 +1295,12 @@ export class SpaceStoreClass extends AsyncStoreWithClient<IState> {
                     }
 
                     case "Spaces.showPeopleInSpace":
-                        // getSpaceFilteredUserIds will return the appropriate value
-                        this.emit(payload.roomId);
-                        if (!this.enabledMetaSpaces.some((s) => s === MetaSpace.Home || s === MetaSpace.People)) {
-                            this.updateNotificationStates([payload.roomId]);
+                        if (payload.roomId) {
+                            // getSpaceFilteredUserIds will return the appropriate value
+                            this.emit(payload.roomId);
+                            if (!this.enabledMetaSpaces.some((s) => s === MetaSpace.Home || s === MetaSpace.People)) {
+                                this.updateNotificationStates([payload.roomId]);
+                            }
                         }
                         break;
 
@@ -1353,7 +1356,7 @@ export class SpaceStoreClass extends AsyncStoreWithClient<IState> {
         return sortBy(spaces, [this.getSpaceTagOrdering, "roomId"]);
     }
 
-    private async setRootSpaceOrder(space: Room, order: string): Promise<void> {
+    private async setRootSpaceOrder(space: Room, order?: string): Promise<void> {
         this.spaceOrderLocalEchoMap.set(space.roomId, order);
         try {
             await this.matrixClient?.setRoomAccountData(space.roomId, EventType.SpaceOrder, { order });