Update error handling according to the latest Search API change

If a patch along the lines of #1551302-12: Fix server tasks system is added to the Search API, it will be an API change regarding how service classes should handle errors. While previously a lot of methods couldn't throw exceptions (leading to stale data if the service class didn't implement some retry mechanism), they (or at least four for which this has now been added) are now encouraged to do so when an error occurs. The Search API then handles retrying of the operation later automatically during cron runs.

To use this new feature, we simply have to remove the try/catch clauses from some of our method (or, in one case, re-throw an exception as the underlying one has a too broad type).