sop_verifications_get_time and sop_verifications_get_mode are inconsistent

The former returns a sentinel to indicate an out-of-bounds access, whereas the latter returns an error code.

For me, as a consumer of an API, consistency is paramount, and certainly trumps saving a few keystrokes here and there. I feel like I made that point already, and we don't make progress on that question, so I think we should reach out to other people.

I asked D what is more important to her when she uses a library: consistency, or minimizing the size of the consumer code, and without hesitation she said consistency. I then mentioned this concrete example, and she found it to be inconsistent in an annoying way.