Refactor/check metadata

[consolethinks]

Refactors checkMetadata:

• improvements
• error handling instead of logging
• render some internal functions public for better flexibility down the line

[minottic]

I think this additional functions, as they do non trivial stuff, are worth testing

[consolethinks]

There are no new additional functions, and they're implicitly tested by the main test case. I can write tests for them, but at that point those will be new additions.

[minottic]

you are right, my bad