Well there's also no sensefull error message if you hammer your
head against the monitor.

But there should be....and there is if you bang your head or your keyboard.

The following is the result of me actually banging my head on my keyboard:

uij

😀

You should be capable of hitting a LOT more keys at once.

Maybe unknown options could output some warning if that's
possible with the current parsing.

It is possible, but it has to be done separately for each command.