Diagnostic Support

[PythooonUser]

Summary

The language server should support publishing diagnostics of code issues while the user is typing.

We should compile a list of all possible issues that we want to support.

There are four levels of diagnostic severities that we can use.

Maybe certain types of diagnostics can be made configurable in order to hide them (mostly for warnings).

Errors

Code	Message
100	Unexpected token

Warnings

Code	Message
200	Symbol is defined by never used