If you are getting a message such as
rake aborted!
You have a nil object when you didn't expect it!
You might have expected an instance of Array.
The error occurred while evaluating nil.map
when you try to run Resque workers (for example by QUEUE=* rake environment resque:work), then here is the solution: http://github.com/defunkt/resque/issues/110
I’m simply posting here because Google did not turn up that Github issue in all my variations on the above search terms. I’m also including the actual solution, posted by Github user djanowski:
djanowski 2 days ago | link
Hello,
The issue is that Redis changed this behavior: before, calling commands operating on non-existent keys would return nil. Now it returns the same result as a key containing an empty structure.
On the other hand, the Ruby client had a bug that was treating a nil response from Redis as an empty array. This was fixed in 2.0.1. So now the client correctly reflects Redis’ behavior.
Thus, your options are:* Use redis-rb 2.0.0.
* Upgrade Redis to a more recent version (something later than antirez/redis@4e27f26).
* Patch Resque to handle this bug (less optimal in my view). Basically: redis.smembers(:workers) || [].
