Web Interface failing with Internal Server Error

[rjhancock]

We've been using Rescue for several years now and never really had any issues with it so great job on that. Lately we've been having an odd issue that we're still a bit flummoxed on as we're not sure HOW it's happening.

Redis 7.0.8
Resque 2.4.0
Resque Pool 0.7.0
Resque Scheduler 4.8.0
ActiveScheduler 0.7.0
Ruby 3.0.0

In our setup, before we queue a task we loop through all queues and see if it's currently queued up somewhere, including the failure queue that we will retry every 30 minutes. Somehow an empty string is being added to the failure queue list in Redis and the system crashes with a JSONParse error. I'm still trying to figure out how that is happening.

I can try to submit a PR to have a safety fix for checking for an empty string but it would take time to hunt down where the best place would be for it as it only occurs on the failure queue.