[BUG] Serializing/deserializing objects (eg: asynq.Client) into a task doesn't work as expected

[dray92]

Describe the bug For testing purposes, I have a task obj that stores a reference to the asynq.Client object (I have tested w/ both pointer and non-pointer). When the task is deserialized and processed by the worker, the field for async.Client is not set.

To Reproduce Steps to reproduce the behavior (Code snippets if applicable):

1. Run redis
2. Enqueue task that looks like this:

   type emailTaskPayload struct {
      // ID for the email recipient.
      UserID int
      Client asynq.Client // *asynq.Client
   }
   

3. Handler looks like this (slightly modified from docs):

   func HandleWelcomeEmailTask(ctx context.Context, t *asynq.Task) error {
   var p emailTaskPayload
   if err := json.Unmarshal(t.Payload(), &p); err != nil {
   	return err
   }
   log.Printf(" [*] Send Welcome Email to User %d", p.UserID)
   
   log.Printf("actual deserialized client: %+v", p.Client)
   
   info, err := p.Client.Enqueue(asynq.NewTask(TypeWelcomeEmail, t.Payload()))
   if err != nil {
   	log.Fatal(err)
   }
   log.Printf(" [*] Successfully enqueued task: %+v", info)
   
   return nil
   } 
   

4. See Error

   2023/09/22 01:17:25  [*] Send Welcome Email to User 42
   2023/09/22 01:17:25 actual deserialized client: {broker:<nil>}
   asynq: pid=4171748 2023/09/22 01:17:25.372155 ERROR: recovering from panic. See the stack trace below for details:
   goroutine 24 [running]:
   runtime/debug.Stack()
           /home/devzero/.goenv/versions/1.20.3/src/runtime/debug/stack.go:24 +0x65
           ....... more stuff
   

Expected behavior Worker is able to deserialize the client object and use it to publish a new task.

Screenshots ~~If applicable, add screenshots to help explain your problem.~~

Environment (please complete the following information):

• OS: Linux
• Version of asynq package: v0.24.1

Additional context Add any other context about the problem here.

[dray92]

The workaround when people face issues like these:

• initializing the relevant clients as part of the worker process
• running the worker process as part of the main process, maybe using goroutines etc