[Discussion] Add solid Error messages

[azerupi]

When using the cli tool there should be solid error messages explaining exactly what went wrong, if it is a parsing error add line numbers, ...

Non-fatal errors should not cause mdBook to stop. They should be stored and reported at the end.

How can this be done? What would be a good design?

Inspiration

• Cargo

[Michael-F-Bryan]

It looks like error-chain is quickly becoming the de-facto tool for doing good error handling. In particular, the rust cookbook is pushing it as the way to do error handling in all examples.

Would it be a good idea to switch to using error-chain instead of std::io::Error or Box<Error> everywhere? I feel like the chain_err() method in particular would help with returning a nice human-readable message to the user, while still retaining all the information necessary to help with debugging.

Coupling error-chain with more robust algorithms (e.g. trying fallbacks when an operation returns an Err instead of erroring out) would probably greatly improve the error handling story for mdbook.

[azerupi]

Yes, error-chain was already pulled in as a dependency for the build script to 'test out'. I haven't had the time yet to catch up with what error-chain can do, but I've heard a lot of good. So I'm ok to start using it pervasively throughout the code base :)

[Dylan-DPC-zz]

Closing this issue due to inactivity. If needed we can discuss this in an new issue. Thanks

[Michael-F-Bryan]

Thanks @Dylan-DPC. I think we should have closed the issue after merging #361.