Improve error origin reporting for companion-related errors

[joao-paulo-parity]

Problem: The error from #349 happened due to a parsing error for the description of paritytech/cumulus#870 (comment), but it was reported on the Substrate PR paritytech/substrate#10463 (comment) with no way to trace it back to the source of the problem without looking at the logs.

Solution: The error message should include where the error originated from, as in

Error ...
While trying to parse the description of paritytech/cumulus#870

[joao-paulo-parity]

This might have been fixed by #354

[mordamax]

@joao-paulo-parity is that it?

or some other cases still missing for this scope of issue?

[joao-paulo-parity]

This one is about a different problem. That being said I think it is working properly now, so it's better to create a new issue in case this comes up again.