This bug was the reason i had to delete multiple worlds. Sometimes this would happen if a pre-release or release comes out.
MC-148152
chunk corruptions
Resolved
Invalid
0
Snapshots (and pre-releases) might and sometimes will break your world. That's why you're advised to make backups of it.
The chunk corruption probably came from a bug in 1.14-pre1 (MC-147754) and has been fixed in 1.14-pre2. There's no way to fix affected worlds retroactively.