[refactor]: Fix CI lints after bump of toolchain version

[mversic]

Description

Fixed CI lints

missing_panics_doc now fires for every public function that calls Option::expect or Result::expect. In some cases (like Metadata) I've extracted the panicking into a special private function because I don't think it's a good solution to just slap missing_panics_doc on every function that asserts invariants. We definitely want to get rid of these warnings, but what to do about it?

Linked issue

Closes #{issue_number}

Benefits

Checklist

• I've read CONTRIBUTING.md
• I've used the standard signed-off commit format (or will squash just before merging)
• All applicable CI checks pass (or I promised to make them pass later)
• (optional) I've written unit tests for the code changes
• I replied to all comments after code review, marking all implemented changes with thumbs up

[coveralls]

Pull Request Test Coverage Report for Build 7527153546

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+1.0%) to 57.042%

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Totals
Change from base Build 7285255818:	1.0%
Covered Lines:	22489
Relevant Lines:	39425

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💛 - Coveralls