Change behavior to close after queue is empty

Currently yootils queue is set to close before actually finishing the promise, making it unpractical to add a task, await queue.close() and in that task adding more tasks, which will currently fail because close = true is set on calling awaiting close.

yootils/src/async/queue.ts

Lines 58 to 68 in 79070c4

    
           close() { 
        
           	closed = true; 
        
           	return new Promise((fulfil, reject) => { 
        
           		if (pending === 0) { 
        
           			fulfil(); 
        
           		} else { 
        
           			fulfil_closed = fulfil; 
        
           		} 
        
           	}); 
        
           }

Thank you! Sorry for the delayed response. I'm not sure if these are the most desirable semantics though — isn't it confusing if you can add a task after calling q.close()?

I do like the idea of q.close returning a promise that resolves when all items have completed though.

Yeah, I agree, it was mainly a fix to sveltejs/sapper#604 and it's more a closeWhenEmpty now.

Found an alternative solution in sveltejs/sapper#605, so we can keep the existing semantics of q.close — I'll close this. I've merged the additional tests from #4 though — thank you!

	close() {
	closed = true;

	return new Promise((fulfil, reject) => {
	if (pending === 0) {
	fulfil();
	} else {
	fulfil_closed = fulfil;
	}
	});
	}