Fix not loaded tick schedule warning in world gen

"Trying to schedule tick in not loaded position" can log in MC 1.21.4 when sand or other FallingBlock.class blocks attempt to generate in a DH context (IE the chunk isn't loaded in the server).

fabric/src/main/java/com/seibel/distanthorizons/fabric/mixins/server/MixinLevelTicks.java

@@ -0,0 +1,33 @@
+package com.seibel.distanthorizons.fabric.mixins.server;
+
+import com.seibel.distanthorizons.common.wrappers.DependencySetupDoneCheck;
+
+import net.minecraft.world.ticks.LevelTicks;
+import net.minecraft.world.ticks.ScheduledTick;
+
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
+
+@Mixin(LevelTicks.class)
+public class MixinLevelTicks<T>
+{
+	// TODO put in a common location
+	private static boolean isWorldGenThread()
+	{ return DependencySetupDoneCheck.isDone && DependencySetupDoneCheck.getIsCurrentThreadDistantGeneratorThread.get(); }
+	
+	
+	
+	@Inject(method = "schedule", at = @At(value = "HEAD"), cancellable = true)
+	private void onChunkSave(ScheduledTick<T> tick, CallbackInfo ci)
+	{
+		// In MC 1.21.4 an error check was added to log attempting to schedule ticks for unloaded chunks
+		// this caused a lot of unnecessary errors when generating sand (FallingBlock.class).
+		if (isWorldGenThread())
+		{
+			ci.cancel();
+		}
+	}
+	
+}

fabric/src/main/resources/DistantHorizons.fabric.mixins.json

@@ -8,7 +8,8 @@
     "server.MixinEntity",
     "server.MixinServerPlayer",
     "server.MixinTracingExecutor",
-    "server.MixinUtilBackgroundThread"
+    "server.MixinUtilBackgroundThread",
+    "server.MixinLevelTicks"
   ],
   "client": [
     "client.MixinClientLevel",