SignalWithStartWorkflow - racy with this pattern?

I’m wondering whether this pattern is safe to use as a target for SignalWithStartWorkflow:

func (wf *MyWorkflow) ControlLoop(ctx workflow.Context, someID string) (err error) {
	for {
		evt := wf.pollLastEvent(ctx)
		if evt == nil {
			break  // *** HERE

		err = workflow.ExecuteChildWorkflow(
		    /* launch a handler workflow - the point of this is to serialise signal processing */
                ) // etc
        // nothing left to do, so quit the workflow
	return err

I think the issue here is that this control loop can poll and discover no signals pending (the // HERE) and proceed to exit - as another signal arrives for processing. The workflow is “already running” so we see a warning: “Workflow has unhandled signals”

I’ve seen claims elsewhere that the above pattern is safe and that the workflow should be restarted; but I can’t find any solid documentation on this, and that doesn’t jibe with my observations. (The motivation for the above pattern was primarily to not have a bazillion idle workflows knocking around in a UI.)

Would appreciate a definitive answer “this is supposed to work” or “that is not guaranteed to work, don’t do it” so we can make some progress with this.

What is the code for the pollLastEvent?

Apologies - just grabs the associated channel (there’s one) and calls ReceiveAsync on it.
The original intention was to drain down a channel, then have the workflow quit.

Then, I believe this code shouldn’t lose signals.