docs: Describe how to handle Options as errors

[har7an]

Extend the error handling documentation.

@imsnif: You said you wanted to mention the bit about returning an anyhow::Result mentioned in CONTRIBUTING.md. I'm honestly not sure where it fits in there, and I don't want to bloat it needlessly... So I extended the error handling docs and added a TL;DR:

Is that alright for you, too?

[imsnif]

@har7an - this looks great! How about duplicating this in CONTRIBUTING.md under the title How to propagate errors from your functions?

[har7an]

I feel like it's a little out of place in CONTRIBUTING.md to be honest. This is sort of a very concrete tip for how to code. Like, where do you draw the line for things we care to mention there?

Since it's likely the first file (after README.md) that potential contributors will read, I wouldn't want to strike them with a wall of text as it grows. I agree we should somehow reference it, but I'm not sure how. Maybe we add a section Tips for code contributions, or Zellij coding best practices and then stick a few very brief examples in there (the TL;DR in this case) along with links to "further reading" (Like the new section in ERROR_HANDLING.md in this case)?

[imsnif]

Since it's likely the first file (after README.md) that potential contributors will read, I wouldn't want to strike them with a wall of text as it grows. I agree we should somehow reference it, but I'm not sure how. Maybe we add a section Tips for code contributions, or Zellij coding best practices and then stick a few very brief examples in there (the TL;DR in this case) along with links to "further reading" (Like the new section in ERROR_HANDLING.md in this case)?

Sounds good!