Quality Error reporting

[BenWeber42]

There has been no focus on good and human readable error messages so far. Attempts have been made to allow good solutions in the future, but they are very incomplete currently.

[BenWeber42]

This will probably also require a complete overhaul of the exception hierarchy, so errors can be classified into categories such as grammar errors, semantic errors, internal errors, etc.

Infrastructure and utility will probably be needed to support better error reporting. E.g., the transform decorator could help in error reporting.