Loaded into the world and discovered it as the blank seed, the files in the DB file were:

000003.log (was empty when opened)

Manifest

CURRENT

was using structure blocks before the occured

Steps To Reproduce:

1. Do copy and paste with structure block
2. leave world and minecraft
3. closed of pc 
4. opened minecraft and DB was corrupt

observed results:

db file being corrupted

expected results:

db file being corrupted