Minor type checking improvement for cluster.queue method

[cyxou]

First of all, thank you for your work!
I have a minor suggestion on improving type checking fot the cluster.queue() method.
Now we have this:

public async queue(
        data: JobData | TaskFunction,
        taskFunction?: TaskFunction,
    ): Promise<void> {
...
}

As one can inspect, JobData is of type any and it is used both as a first argument to cluster.queue() method as well as the data property of the TaskFunctionArguments interface. This approach does not provide sufficient type checking when we call the cluster.queue() method with two arguments. I'd suggest to use generic types here like this:

type QueueFunction<T> = (arg: QueueFunctionArguments<T>) => Promise<void>;

interface QueueFunctionArguments<T> {
  page: puppeteer.Page;
  data: T;
  worker: {
    id: number;
  };
}

public async queue<T>(
    data: T | TaskFunction,
    taskFunction?: QueueFunction<T>,
): Promise<void> {
...
}

[thomasdondorf]

Looks good. As this might break implementations, I'll put this into the roadmap for v1 (#8).

[thomasdondorf]

This could actually be implemented without being a breaking change by using any as default for the generics.

[thomasdondorf]

I just implemented this. You can now specify the types for input/output via Cluster<input, output>. output is used when execute is called.