Suggest `brew update && …` when handling errors or missing methods

As @ndr-qef and @rolandwalker suggested on IRC.

This is supposed to help cut trivial issues that would be easily fixable by doing `brew update && …` etc.
Also, splitting unit tests in two to keep one from triggering the other.

I’ve been taught that lines longer than 80 chars are bad.
Sometimes this makes me feel so guilty that I even try to follow this rule in herestrings. :blush:

Am I free to ignore this rule in herestrings? Or maybe you happen to know a less confusing way to soft-wrap long lines?