Fix incorrect old oversized chunk data merging

All legacy oversized chunks were created before the new
chunk format, so don't try to merge into the new format.

patches/server/Allow-Saving-of-Oversized-Chunks.patch

@@ -191,8 +191,8 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +                }
 +                CompoundTag oversizedLevel = oversizedData.getCompound("Level");
 +
-+                mergeChunkList(chunk, oversizedLevel, "entities", "Entities");
-+                mergeChunkList(chunk, oversizedLevel, "block_entities", "TileEntities");
++                mergeChunkList(chunk.getCompound("Level"), oversizedLevel, "Entities", "Entities");
++                mergeChunkList(chunk.getCompound("Level"), oversizedLevel, "TileEntities", "TileEntities");
 +
 +                return chunk;
 +            } catch (Throwable throwable) {