Try opening the database with something like
DB Browser for SQLite, and see what happens when you browse around. If it throws an error then its highly probable the db is genuinely corrupt.
Do you have any library backups? If so might be an idea to restore the latest one.
You could try rebuilding the database with via Library maintenance->Restore database and do the Check Library again.
Corruption of SQLite databases is very, very rare, almost always due to hardware faults. So aftre rebuilding the database I suggest you backup your data and run some diagnostic tests on your hard drive, it maybe on the point of catastrophic failure.
BR