Fix some invalid SearchController tests.

The implementation changed and the affirmative tests changed, but the
negative ones got left behind.

Signed-off-by: Alex Welch <me@alexwelch.com>
Rescue and surface errors during searches.

This is our first pass and we're not handling any specific exceptions
that we know might be the common, like Faraday parsing error or 404 or
something. Right now the error is pretty generic.

Signed-off-by: Alex Welch <me@alexwelch.com>