fixed panics on msg.Name != "" & redis is disabled

[mvisonneau]

When using the tool without redis, if the Name of a taskq.Message is set, we end up with the following error:

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x48 pc=0xa3dcac]

goroutine 1 [running]:
github.com/vmihailenco/taskq/v3.redisStorage.Exists(0x0, 0x0, 0xf1bf30, 0xc00002a0b8, 0xc0005fe120, 0x13, 0x13)
        /home/max/go/pkg/mod/github.com/vmihailenco/taskq/v3@v3.2.3/taskq.go:66 +0x4c
github.com/vmihailenco/taskq/v3/memqueue.(*Queue).isDuplicate(0xc00059e980, 0xc000580b60, 0x0)
        /home/max/go/pkg/mod/github.com/vmihailenco/taskq/v3@v3.2.3/memqueue/queue.go:263 +0x8e
github.com/vmihailenco/taskq/v3/memqueue.(*Queue).Add(0xc00059e980, 0xc000580b60, 0x12, 0xc00059ab70)
        /home/max/go/pkg/mod/github.com/vmihailenco/taskq/v3@v3.2.3/memqueue/queue.go:179 +0x5

[vmihailenco]

I think I prefer to see an error when storage is not configured. I am not sure that local storage is a good default choice (+ it adds extra dependency).

You can still set opt.Storage = localStorage{} in your app when configuring a queue...

[shaunco]

You can still set opt.Storage = localStorage{} in your app when configuring a queue...

Only if localStorage becomes LocalStorage or a NewLocalStorage() function is added... otherwise localStorage is only usable internal to taskq.

...

As a user of taskq via memqueue instead of Redis, this finally allows us to name tasks and prevent duplicates. That said, I find it very strange that named tasks will always Exists once added to a queue when it seems like they should stop existing once successfully executed... but Storage only has a single Exists method, which means Consumer has no way to remove a successfully executed task from storage.

[shaunco]

Seems like this can be closed since #162 was accepted. Might be worth noting in the readme opt.Storage = taskq.NewLocalStorage() should be set to make use of names.