stale progress reporting

[akosyakov]

I've noticed that progress reporting in the explorer runs forever sometimes. During debugging of such cases I see that all progress tasks are properly cleaned up but progress is still rendered.

I think there is a race condition here:

theia/packages/core/src/browser/progress-location-service.ts

Lines 68 to 76 in d0e00c5

	this.fireEvent(locationId, show);
	}
	protected readonly fireEvent = throttle((locationId: string, show: boolean) => {
	let emitters = this.emitters.get(locationId);
	if (!emitters) {
	emitters = [ this.addEmitter(locationId) ];
	}
	emitters.forEach(e => e.fire({ show }));
	}, 250);

If several progresses running the last one win cancel out event for previous, so the explorer location never sees done event for instance.

cc @AlexTugarev

[vince-fugnitto]

I noticed it today for the debug view:

If it helps, here are the reproduction steps:

1. open the debug view
2. click the Start Debugging button ('attach by process id' was selected)
3. press esc
4. the progress will be displayed always