Have a better error message in case of a schema mismatch

[Fokko]

Feature Request / Improvement

When a schema doesn't match, we currently just present the two schema's. It would be great to explicitly tell the user what the difference is between the schemas.

[MehulBatra]

@Fokko If the situation allows I would love to take a shot at it.

[Fokko]

@MehulBatra Thanks, but I think this was already fixed by #352