Hoist out synchronisation from ChunkRegionLoader

By: md_5 <git@md-5.net>

paper-server/nms-patches/ChunkProviderServer.patch

@@ -84,7 +84,7 @@
                              ++i;
                          }
                      }
-@@ -267,6 +291,40 @@
+@@ -267,6 +291,42 @@
          return false;
      }
  
@@ -112,12 +112,14 @@
 +            }
 +        }
 +        // Moved from unloadChunks above
-+        chunk.removeEntities();
-+        if (save) {
-+            this.saveChunk(chunk);
++        synchronized (this.chunkLoader) {
++            chunk.removeEntities();
++            if (save) {
++                this.saveChunk(chunk);
++            }
++            this.chunks.remove(chunk.chunkKey);
++            this.lastChunk = null;
 +        }
-+        this.chunks.remove(chunk.chunkKey);
-+        this.lastChunk = null;
 +        return true;
 +    }
 +    // CraftBukkit end