|That's pretty clear. You need to tell bluetoothctl how long to wait e.g.
bluetoothctl --timeout 2 should time out after 2 seconds. Who knows, maybe you could even use a floating point value e.g.
--timeout 1.5 for finer grain control.
Normally, though, a long option is specified as
--timeout=2, so you might try that as well if the above does not work. I've checked a few of web sites, but none of them were able to help in this regard. Still a little experimentation on your part should clear that up. When you get it sorted, maybe post a note the to the maintainers that it needs to be explained better.
Keep Calm and Carry On