Refactor: shorten & un-nest functions, re-think return values

[Lotterleben]

Opening this issue for visibility (and also because I'd like to do this :D)
Imo it'd help with readability and maintainability to do a refactoring run.

Things that I've been bumping into:

• checks in notmain() could be pulled into separate functions for readability
• construct_backtrace() is pretty long and involved; amount of parameters is smelly
• construct_backtrace() always returns OK, even if there was an exception (then it's an OK(Some(TopException))). Returning a Result<(), TopException> would be more intuitive imo, but this could also be that I'm misunderstanding anyhow::Error
• update_cfa()has another unintuive return value, could be Option<new_cfa> imo

These can also be sneaked in as drive-bys on bugfixes and feature implementation.

[Urhengulas]

Totally agree that there is room for quite some refactoring!

Also we might want to add some unit, but also end-to-end tests. Maybe the kind of @jonas-schievink described in the github-actions blog Post :)

[Lotterleben]

very much agreed! I've tracked that one in #173 :D Maybe we can chat about planning/funds for this in the next bi-weekly?

[japaric]

construct_backtrace was refactored in PR #197

[Urhengulas]

@Lotterleben Do you consider this resolved by #222?

[Lotterleben]

very much so! thanks for the bump