diff --git a/src/core/annotation.js b/src/core/annotation.js
index 252e1529b4849..3241152d76882 100644
--- a/src/core/annotation.js
+++ b/src/core/annotation.js
@@ -25,6 +25,7 @@ import {
   escapeString,
   getModificationDate,
   isString,
+  objectSize,
   OPS,
   shadow,
   stringToPDFString,
@@ -1326,7 +1327,7 @@ class WidgetAnnotation extends Annotation {
 
   _computeFontSize(font, fontName, fontSize, height) {
     if (fontSize === null || fontSize === 0) {
-      const em = font.charsToGlyphs("M", true)[0].width / 1000;
+      const em = font.charsToGlyphs("M")[0].width / 1000;
       // According to https://en.wikipedia.org/wiki/Em_(typography)
       // an average cap height should be 70% of 1em
       const capHeight = 0.7 * em;
@@ -1460,18 +1461,20 @@ class WidgetAnnotation extends Annotation {
     if (dict.has("AA")) {
       const additionalActions = dict.get("AA");
       for (const key of additionalActions.getKeys()) {
-        if (key in AnnotationActionEventType) {
-          const actionDict = additionalActions.getRaw(key);
-          const parents = new RefSet();
-          const list = [];
-          this._collectJS(actionDict, xref, list, parents);
-          if (list.length > 0) {
-            actions[AnnotationActionEventType[key]] = list;
-          }
+        const action = AnnotationActionEventType[key];
+        if (!action) {
+          continue;
+        }
+        const actionDict = additionalActions.getRaw(key);
+        const parents = new RefSet();
+        const list = [];
+        this._collectJS(actionDict, xref, list, parents);
+        if (list.length > 0) {
+          actions[action] = list;
         }
       }
     }
-    // Collect the Action if any (we may have one on pushbutton)
+    // Collect the Action if any (we may have one on pushbutton).
     if (dict.has("A")) {
       const actionDict = dict.get("A");
       const parents = new RefSet();
@@ -1481,7 +1484,7 @@ class WidgetAnnotation extends Annotation {
         actions.Action = list;
       }
     }
-    return actions;
+    return objectSize(actions) > 0 ? actions : null;
   }
 
   getFieldObject() {
@@ -1597,7 +1600,7 @@ class TextWidgetAnnotation extends WidgetAnnotation {
     }
 
     const scale = fontSize / 1000;
-    const whitespace = font.charsToGlyphs(" ", true)[0].width * scale;
+    const whitespace = font.charsToGlyphs(" ")[0].width * scale;
     const chunks = [];
 
     let lastSpacePos = -1,
@@ -1618,7 +1621,7 @@ class TextWidgetAnnotation extends WidgetAnnotation {
           lastSpacePos = i;
         }
       } else {
-        const charWidth = font.charsToGlyphs(character, false)[0].width * scale;
+        const charWidth = font.charsToGlyphs(character)[0].width * scale;
         if (currentWidth + charWidth > width) {
           // We must break to the last white position (if available)
           if (lastSpacePos !== -1) {
diff --git a/src/core/fonts.js b/src/core/fonts.js
index 3839a701bc1da..6f8d60b319f10 100644
--- a/src/core/fonts.js
+++ b/src/core/fonts.js
@@ -3208,7 +3208,10 @@ var Font = (function FontClosure() {
       return shadow(this, "spaceWidth", width);
     },
 
-    charToGlyph: function Font_charToGlyph(charcode, isSpace) {
+    /**
+     * @private
+     */
+    _charToGlyph(charcode, isSpace = false) {
       var fontCharCode, width, operatorListId;
 
       var widthCode = charcode;
@@ -3332,13 +3335,13 @@ var Font = (function FontClosure() {
           i += length;
           // Space is char with code 0x20 and length 1 in multiple-byte codes.
           var isSpace = length === 1 && chars.charCodeAt(i - 1) === 0x20;
-          glyph = this.charToGlyph(charcode, isSpace);
+          glyph = this._charToGlyph(charcode, isSpace);
           glyphs.push(glyph);
         }
       } else {
         for (i = 0, ii = chars.length; i < ii; ++i) {
           charcode = chars.charCodeAt(i);
-          glyph = this.charToGlyph(charcode, charcode === 0x20);
+          glyph = this._charToGlyph(charcode, charcode === 0x20);
           glyphs.push(glyph);
         }
       }
diff --git a/src/core/obj.js b/src/core/obj.js
index 9aeb8f4a5904f..f45fc40ea19b3 100644
--- a/src/core/obj.js
+++ b/src/core/obj.js
@@ -25,7 +25,7 @@ import {
   isBool,
   isNum,
   isString,
-  objectFromEntries,
+  objectSize,
   PermissionFlag,
   shadow,
   stringToPDFString,
@@ -787,7 +787,7 @@ class Catalog {
    */
   get openAction() {
     const obj = this._catDict.get("OpenAction");
-    const openActionMap = new Map();
+    const openAction = Object.create(null);
 
     if (isDict(obj)) {
       // Convert the OpenAction dictionary into a format that works with
@@ -799,17 +799,17 @@ class Catalog {
       Catalog.parseDestDictionary({ destDict, resultObj });
 
       if (Array.isArray(resultObj.dest)) {
-        openActionMap.set("dest", resultObj.dest);
+        openAction.dest = resultObj.dest;
       } else if (resultObj.action) {
-        openActionMap.set("action", resultObj.action);
+        openAction.action = resultObj.action;
       }
     } else if (Array.isArray(obj)) {
-      openActionMap.set("dest", obj);
+      openAction.dest = obj;
     }
     return shadow(
       this,
       "openAction",
-      openActionMap.size > 0 ? objectFromEntries(openActionMap) : null
+      objectSize(openAction) > 0 ? openAction : null
     );
   }
 
diff --git a/src/shared/util.js b/src/shared/util.js
index ab1f58aef2dda..c49e6e30c1538 100644
--- a/src/shared/util.js
+++ b/src/shared/util.js
@@ -585,6 +585,10 @@ function string32(value) {
   );
 }
 
+function objectSize(obj) {
+  return Object.keys(obj).length;
+}
+
 // Ensures that the returned Object has a `null` prototype.
 function objectFromEntries(iterable) {
   return Object.assign(Object.create(null), Object.fromEntries(iterable));
@@ -1040,6 +1044,7 @@ export {
   isString,
   isSameOrigin,
   createValidAbsoluteUrl,
+  objectSize,
   objectFromEntries,
   IsLittleEndianCached,
   IsEvalSupportedCached,