Clear lastSection on game event listener removal (fixes #87)

src/main/java/ca/spottedleaf/moonrise/mixin/chunk_system/DynamicGameEventListenerMixin.java

@@ -0,0 +1,25 @@
+package ca.spottedleaf.moonrise.mixin.chunk_system;
+
+import net.minecraft.core.SectionPos;
+import net.minecraft.world.level.gameevent.DynamicGameEventListener;
+import org.jetbrains.annotations.Nullable;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Shadow;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
+
+@Mixin(DynamicGameEventListener.class)
+abstract class DynamicGameEventListenerMixin {
+    @Shadow @Nullable private SectionPos lastSection;
+
+    @Inject(method = "remove", at = @At("RETURN"))
+    private void onRemove(final CallbackInfo ci) {
+        // We need to unset the last section when removed, otherwise if the same instance is re-added at the same position it
+        // will assume there was no change and fail to re-register.
+        // In vanilla, chunks rarely unload and re-load quickly enough to trigger this issue. However, our chunk system has a
+        // quirk where fast chunk reload cycles will often occur on player login (see PR #22).
+        // So we fix this vanilla oversight as our changes cause it to manifest in bugs much more often (see issue #87).
+        this.lastSection = null;
+    }
+}

src/main/resources/moonrise.mixins.json

@@ -26,6 +26,7 @@
         "chunk_system.ChunkStepMixin",
         "chunk_system.ChunkStorageMixin",
         "chunk_system.DistanceManagerMixin",
+        "chunk_system.DynamicGameEventListenerMixin",
         "chunk_system.EntityGetterMixin",
         "chunk_system.EntityMixin",
         "chunk_system.EntityTickListMixin",