Fix #516

Author: Sollace

src/main/java/com/minelittlepony/unicopia/ability/magic/spell/PlacementControlSpell.java

@@ -20,11 +20,12 @@
 import net.minecraft.registry.RegistryKeys;
 import net.minecraft.registry.RegistryWrapper.WrapperLookup;
 import net.minecraft.util.Identifier;
+import net.minecraft.util.Util;
 import net.minecraft.util.math.Vec3d;
 import net.minecraft.world.World;
 
 public class PlacementControlSpell extends AbstractSpell implements OrientedSpell {
-    private final DataTracker.Entry<UUID> placedEntityId = dataTracker.startTracking(TrackableDataType.UUID, null);
+    private final DataTracker.Entry<UUID> placedEntityId = dataTracker.startTracking(TrackableDataType.UUID, Util.NIL_UUID);
     private final DataTracker.Entry<Optional<RegistryKey<World>>> dimension = dataTracker.startTracking(TrackableDataType.ofRegistryKey(), Optional.empty());
     private final DataTracker.Entry<Optional<Vec3d>> position = dataTracker.startTracking(TrackableDataType.OPTIONAL_VECTOR, Optional.empty());
     private final DataTracker.Entry<Optional<Vec3d>> orientation = dataTracker.startTracking(TrackableDataType.OPTIONAL_VECTOR, Optional.empty());
@@ -82,7 +83,7 @@ public boolean apply(Caster<?> caster) {
     public boolean tick(Caster<?> source, Situation situation) {
         if (!source.isClient()) {
 
-            if (placedEntityId.get() == null) {
+            if (Util.NIL_UUID.equals(placedEntityId.getOrDefault(Util.NIL_UUID))) {
                 if (dimension.get().isEmpty()) {
                     setDimension(source.asWorld().getRegistryKey());
                 }
@@ -111,7 +112,7 @@ public boolean tick(Caster<?> source, Situation situation) {
 
     @Nullable
     private Ether.Entry<?> getConnection(Caster<?> source) {
-        return delegate == null || placedEntityId.get() == null ? null : getWorld(source)
+        return delegate == null || Util.NIL_UUID.equals(placedEntityId.getOrDefault(Util.NIL_UUID)) ? null : getWorld(source)
                 .map(world -> Ether.get(world).get(getDelegate().getTypeAndTraits().type(), placedEntityId.get(), delegate.getUuid()))
                 .orElse(null);
     }
@@ -127,16 +128,17 @@ public void toNBT(NbtCompound compound, WrapperLookup lookup) {
         position.get().ifPresent(pos -> compound.put("position", NbtSerialisable.writeVector(pos)));
         orientation.get().ifPresent(o -> compound.put("orientation", NbtSerialisable.writeVector(o)));
         dimension.get().ifPresent(d -> compound.putString("dimension", d.getValue().toString()));
-        if (placedEntityId.get() != null) {
-            compound.putUuid("placedEntityId", placedEntityId.get());
+        @Nullable UUID placeEntityUuid = placedEntityId.getOrDefault(Util.NIL_UUID);
+        if (!Util.NIL_UUID.equals(placeEntityUuid)) {
+            compound.putUuid("placedEntityId", placeEntityUuid);
         }
     }
 
     @Override
     public void fromNBT(NbtCompound compound, WrapperLookup lookup) {
         super.fromNBT(compound, lookup);
         delegate = Spell.readNbt(compound.getCompound("spell"), lookup);
-        placedEntityId.set(compound.containsUuid("placedEntityId") ? compound.getUuid("placedEntityId") : null);
+        placedEntityId.set(compound.containsUuid("placedEntityId") ? compound.getUuid("placedEntityId") : Util.NIL_UUID);
         position.set(compound.contains("position") ? Optional.of(NbtSerialisable.readVector(compound.getList("position", NbtElement.DOUBLE_TYPE))) : Optional.empty());
         orientation.set(compound.contains("orientation") ? Optional.of(NbtSerialisable.readVector(compound.getList("orientation", NbtElement.DOUBLE_TYPE))) : Optional.empty());
         dimension.set(compound.contains("dimension", NbtElement.STRING_TYPE) ? Optional.ofNullable(Identifier.tryParse(compound.getString("dimension"))).map(id -> RegistryKey.of(RegistryKeys.WORLD, id)) : Optional.empty());

src/main/java/com/minelittlepony/unicopia/ability/magic/spell/effect/PortalSpell.java

@@ -84,7 +84,7 @@ public float getYawDifference() {
 
     @SuppressWarnings("unchecked")
     private Ether.Entry<PortalSpell> getDestination(Caster<?> source) {
-        return Util.NIL_UUID.equals(targetPortalId.get()) ? null : getDestinationReference()
+        return Util.NIL_UUID.equals(targetPortalId.getOrDefault(Util.NIL_UUID)) ? null : getDestinationReference()
                 .getTarget()
                 .map(target -> Ether.get(source.asWorld()).get((SpellType<PortalSpell>)getType(), target.uuid(), targetPortalId.get()))
                 .filter(destination -> destination.isClaimedBy(getUuid()))
@@ -229,7 +229,10 @@ protected void onDestroyed(Caster<?> caster) {
     @Override
     public void toNBT(NbtCompound compound, WrapperLookup lookup) {
         super.toNBT(compound, lookup);
-        compound.putUuid("targetPortalId", targetPortalId.get());
+        @Nullable UUID otherPortalUuid = targetPortalId.getOrDefault(Util.NIL_UUID);
+        if (!Util.NIL_UUID.equals(otherPortalUuid)) {
+            compound.putUuid("targetPortalId", otherPortalUuid);
+        }
         compound.put("teleportationTarget", teleportationTarget.toNBT(lookup));
         compound.putFloat("pitch", getPitch());
         compound.putFloat("yaw", getYaw());

src/main/java/com/minelittlepony/unicopia/network/track/DataTracker.java

@@ -140,6 +140,11 @@ public T get() {
             return tracker.get(this);
         }
 
+        public T getOrDefault(T def) {
+            T t = get();
+            return t == null ? def : t;
+        }
+
         public void set(T t) {
             tracker.set(this, t);
         }