Improve logging of extension manifest parsing errors (#40082)

Due to using anyhow here, we otherwise lose the relevant error and just
surface a fairly useless error message.

Intentionally not doing this for `extension.json` parsing since that is
deprecated.

Release Notes:

- N/A
1ca2f9871eFinn Evers committed on 10/13/2025, 8:27:00 AM· committed by GitHubparent52cc71e
1 file changedLine totals unavailable