Try fix concurrency issue with render closing

core/src/main/java/com/seibel/distanthorizons/core/render/QuadTree/LodQuadTree.java

@@ -34,6 +34,7 @@ import com.seibel.distanthorizons.core.logging.DhLoggerBuilder;
 import com.seibel.distanthorizons.core.pos.blockPos.DhBlockPos2D;
 import com.seibel.distanthorizons.core.pos.DhSectionPos;
 import com.seibel.distanthorizons.core.render.RenderBufferHandler;
+import com.seibel.distanthorizons.core.render.RenderThreadTaskHandler;
 import com.seibel.distanthorizons.core.render.renderer.AbstractDebugWireframeRenderer;
 import com.seibel.distanthorizons.core.render.renderer.BeaconRenderHandler;
 import com.seibel.distanthorizons.core.render.renderer.IDebugRenderable;
@@ -371,8 +372,18 @@ public class LodQuadTree extends QuadTree<LodRenderSection> implements IDebugRen
 		
 		for (QuadNode<LodRenderSection> node : this.tickNodeHolder.getEnableDeleteChildrenNodes())
 		{
-			if (node == null || node.value == null) { continue; }
+			if (node == null
+				|| node.value == null
+				// only clear the children if there are children to clear
+				|| node.getDirectChildCount() == 0) 
+			{
+				continue; 
+			}
 			
+			// run this on the render thread to hopefully prevent
+			// closing render data while rendering is happening
+			RenderThreadTaskHandler.INSTANCE.queueRunningOnRenderThread("LodQuadTree delayed child cleanup", () -> 
+			{
 				node.deleteAllChildren((childRenderSection) ->
 				{
 					if (childRenderSection != null)
@@ -382,6 +393,7 @@ public class LodQuadTree extends QuadTree<LodRenderSection> implements IDebugRen
 						childRenderSection.close();
 					}
 				});
+			});
 		}
 		
 		//endregion

core/src/main/java/com/seibel/distanthorizons/core/util/objects/quadTree/QuadNode.java

@@ -86,6 +86,17 @@ public class QuadNode<T>
 	
 	
 	
+	/** @return the number of non-null direct child nodes */
+	public int getDirectChildCount()
+	{
+		int count = 0;
+		if (this.nwChild != null) { count++; }
+		if (this.neChild != null) { count++; }
+		if (this.swChild != null) { count++; }
+		if (this.seChild != null) { count++; }
+		return count;
+	}
+	
 	/**
 	 * Use {@link QuadNode#getNonNullChildCount()} if you want the number of non-null child values.
 	 *