Added method and type info in convMethodRef exception

[Horusiath]

Recently my team experienced problems caused by convMethodRef: could not bind to method error when executing our scripts in FSI. However the issue with this error is that it isn't distinctively showing, what has gone wrong (I think usually it's the issue with referenced .dll files).

For us, the only way to actually see what was happening, was to enrich that error message using custom FSI build. Since I think, it'd be helpful for the rest of the community in the future - here's the PR. It includes method name and containing type info along with the actual error message. Example:

error FS0192: internal error: convMethodRef: could not bind to method 'QuerySelectorAll' of type 'System.HapCssExtensionMethods, HtmlAgilityPack, Version=1.0.0.0, Culture=neutral, PublicKeyToken=<token>'

/cc: fsharp/fsharp#857

[forki]

While I think it's great to enrich the error message I think this showing a bigger issue. Internal errors should not surface on user code. So this is either a compiler bug or we need to promote the error to a proper compiler error.

[KevinRansom]

Thank you for improving the message. It would be great to get a repro that highlighted the message shortcomings.