Previously, our text sanitizer code did not trim whitespace before
checking that the string was non-empty. This lead to strings consisting
only of whitespace being treated as valid. Not all our downstream
services (such as libpostal) accept whitespace-only input, so this
causes a rather harsh error.
This PR builds upon the code in https://github.com/pelias/api/pull/1170
and moves the trimming code above the nonEmptyString check. Now, a
whitespace-only input string produces the normal error for empty input.
Fixes https://github.com/pelias/api/issues/1158
Julian Simioni