Prevent server crash on shutdown

core/src/main/java/com/seibel/distanthorizons/core/api/internal/SharedApi.java

@@ -99,7 +99,12 @@ public class SharedApi
 		{
 			ThreadPoolUtil.shutdownThreadPools();
 			DebugRenderer.clearRenderables();
-			MC_RENDER.clearTargetFrameBuffer();
+			
+			if (MC_RENDER != null)
+			{
+				MC_RENDER.clearTargetFrameBuffer();
+			}
+			
 			// shouldn't be necessary, but if we missed closing one of the connections this should make sure they're all closed
 			AbstractDhRepo.closeAllConnections();
 			// needs to be closed on world shutdown to clear out un-processed chunks