fix(backups): pass both stdout and stderr to _extract_error_message in _list_timelines

[SAY-5]

Summary

Closes #1482.

_extract_error_message is declared with two positional arguments (stdout, stderr):

@staticmethod
def _extract_error_message(stdout: str, stderr: str) -> str:

Every other call site in src/backups.py (L214, L457, L531, L747, L811, L1028, L1195) supplies both arguments. The _list_timelines call at L570 was the lone exception:

extracted_error = self._extract_error_message(stderr)

so whenever pgbackrest repo-ls returned a non-zero exit code, the error path raised

TypeError: _extract_error_message() missing 1 required positional argument: 'stderr'

instead of the intended ListBackupsError, masking the underlying backup failure.

Fix

Pass the local output variable (the stdout captured from _execute_command) as the first argument, matching the surrounding convention. One-line change.

Test plan

• python -c 'import ast; ast.parse(open("src/backups.py").read())', syntax OK
• grep _extract_error_message src/backups.py, all 8 call sites now pass two arguments
• CI: integration tests that hit a failing pgbackrest repo-ls (e.g. revoked credentials) should now surface the real error inside ListBackupsError instead of the TypeError

[taurus-forever]

Thank you!

[marceloneppel]

Thanks, @SAY-5!

The CI blocked the merge due to an issue regarding your commit signature. Could you check it?

[SAY-5]

Thanks @marceloneppel! Will re-push with a signed commit shortly.