Remove table entery from c_repos_tables. It will get dropped
Console.log and database log should give you more details on the issue. For sure that, your metadata is corrupted and may need support help to clear the inconsistencies.
Can you please share the complete stack trace of the error.
Also please open a support ticket to resolve the metadata corruption issue.
We need to verify the complete log for this issue. Please share complete log information. It helps to see exactly in which line system throws NullPointerException. Thanks.