Setting WorkerLimit in QueueOptions throws a nil pointer while using a Memqueue

[ericschmar]

Setting the Worker Limit to anything above 0 throws a nil pointer when using a memqueue.

My Setup:

	qf                             = memqueue.NewFactory()
	MessageQueue                   = qf.RegisterQueue(&taskq.QueueOptions{
		Name:            "pipeline-worker",
		MinNumWorker:    int32(runtime.NumCPU()),
		MaxNumWorker:    int32(runtime.NumCPU()),
		WorkerLimit:     5,
		ReservationSize: 1000000,
	})

The error in func (c *Client) obtain(ctx context.Context, key, value string, ttl time.Duration) (bool, error):

invalid memory address or nil pointer dereference [signal SIGSEGV: segmentation violation]
Unable to propagate EXC_BAD_ACCESS signal to target process and panic (see https://github.com/go-delve/delve/issues/852)
Stack:
	0  0x0000000004c20e78 in github.com[/bsm/redislock.]()(*Client).obtain
	    at [/Users/schmar1/go/pkg/mod/github.com/bsm/redislock]()@v0.7.1[/redislock.go:97]()
	1  0x0000000004c2087f in github.com[/bsm/redislock.]()(*Client).Obtain
	    at [/Users/schmar1/go/pkg/mod/github.com/bsm/redislock]()@v0.7.1[/redislock.go:69]()
	2  0x0000000004c21438 in github.com[/bsm/redislock.Obtain]()
	    at [/Users/schmar1/go/pkg/mod/github.com/bsm/redislock]()@v0.7.1[/redislock.go:125]()
	3  0x0000000004c57552 in github.com[/vmihailenco/taskq/v3.]()(*Consumer).lockWorker
	    at [/Users/schmar1/go/pkg/mod/github.com/vmihailenco/taskq/v3]()@v3.2.8[/consumer.go:720]()
	4  0x0000000004c555d0 in github.com[/vmihailenco/taskq/v3.]()(*Consumer).worker
	    at [/Users/schmar1/go/pkg/mod/github.com/vmihailenco/taskq/v3]()@v3.2.8[/consumer.go:468]()
	5  0x0000000004c53cad in github.com[/vmihailenco/taskq/v3.]()(*Consumer).addWorker.func1
	    at [/Users/schmar1/go/pkg/mod/github.com/vmihailenco/taskq/v3]()@v3.2.8[/consumer.go:276]()

[lzap]

Oh thank you for the bugreport, I was debugging this today and only then stumbled upon this issue. Removing the limit solves the problem :-)