Error message description cleanup.

[flofriday]

Example

In quite a view cases the error messages are too verbose. This is often when the error originates in the scope but still get prepended by the typechecker. I think we should only generate the error in the typechecker as it has more information (access to the AST).

I don't think we need the message from the scope as it will only fail if the function cannot be found.

[flofriday]

All really bad errors are already fixed