Check for the authorisation on the repo

Throw the error for non-authorisation on the repo before the task runs.

The issue names no file or test. Start by locating the task entry point and the repository authorization check, then trace the order in which authorization and task execution occur. Done means unauthorized repository access produces an error before the task runs; add or update coverage where the existing test suite handles this behavior.

Written by the indexing model from the issue text.