Keep track of token locations and improve error reporting

[ricardoboss]

No description provided.

[ricardoboss]

The exception report design was inspired by https://github.com/nunomaduro/collision:

[chucker]

The exception report design was inspired by https://github.com/nunomaduro/collision:

Should we be more explicit about how the compiler interprets the code? E.g., "You're trying to assign "invalid", which is a string, to the variable a, which is a number."

[ricardoboss]

Added tips for all exceptions:

[github-actions]

Package	Line Rate	Branch Rate	Complexity	Health
StepLang	86%	70%	1318	✔
Summary	86% (1331 / 1549)	70% (795 / 1141)	1318	✔

Minimum allowed line rate is 30%