changeComplete is not called when a big lag happens at the very start

[signorpipo]

The issue is in this piece of code:

if (insTime > insDelay && insTime < insEndDelay) {
      if (!instance.changeBegan) {
        instance.changeBegan = true;
        instance.changeCompleted = false;
        setCallback('changeBegin');
      }
      setCallback('change');
      setAnimationsProgress(insTime);
    } else {
      if (instance.changeBegan) {
        instance.changeCompleted = true;
        instance.changeBegan = false;
        setCallback('changeComplete');
      }
    }

If u have a very big lag, insTime can be more than insDelay and also more than insEndDelay before ever going into the first if, which means changeBegan will never become true, and therefore, changeComplete will never be called

You can easily repro this by putting a break point on the first if check, and after a few seconds (more than the insEndDelay) break again
U will see that insTime will be outside of the first if, but changeBegan is still false

A possible solution would be to change the first if to:

if (insTime > insDelay && (!instance.changeBegan || insTime < insEndDelay) {