Return INVALID_ARGUMENT status for incorrectly formatted file paths in CommitService::LastCommitForPath
Problem to solve
The service CommitService::LastCommitForPath
returns an internal error with an unhelpful message when given an invalid file path. See this sentry error and this internal comment for details.
Proposal
Return a more relevant status code and error message when given an invalid file path, so that the client can handle it appropriately instead of just failing.