Expose the fields of `Error` as public

[GodTamIt]

These fields can be useful when trying to inspect the error.

[Licenser]

I totally see the use on that, instead of making the fields public would it work for you to add accessor functions? That way, keeping the fields private, allows to change them in the future as needed without forcing users to adopt their code as long as the functions can wrap the new data layout into the old functions.

[GodTamIt]

@Licenser sorry, took a while for me to get back to this but this should be done now :)

[Licenser]

thanks! released as 0.13.10