robfig/cron — pull request #6 by vegasje (2013-08-14 16:50:32+00:00)
Title: Using panic is not a proper way to handle errors.  This assumes that the...

... developer is only ever evaluating static cron specs that aren't configured dynamically. If I wanted to utilize the Parse function in this library, and manage crons through some type of configuration interface, I would have no way to recover from parsing an improperly-formatted spec, other than deferred recover. There is a reason we don't see this practice inside the stdlib. Using errors allows me to recover from that scenario with ease.