Task stuck due to "Error: Reflect task args: test is not xxx"

[niedbalski]

If a task argument value of incorrect type is passed, the tasksignature.Get method get stuck waiting
for a result.

Example client:

    signatures.TaskArg{
            Type:  "int64",
            Value: "this-is-a-string",
    },

    asyncResult, err := server.SendTask(&task)
    if err != nil {
        fmt.Println(err)
    }

    result, err := asyncResult.Get()

The worker displays the following error:

2016/01/04 16:18:47 Failed processing task_488a2edb-433b-4fda-a4eb-d5a59568f3a3. Error = this-is-a-string is not int64
2016/01/04 16:18:47 Going to retry launching the worker. Error: Reflect task args: this-is-a-string is not int64

I think would be better to set the task state to failed, and return the error.