The eventKey string in KeyboardDownHandler can be practically empty and cannot be parsed in those occasions, causing an enum parse error in Event.KeyboardEvent, or crash if exceptions are disabled.

The content of the string in these occasions is #, ^ or &.

instance.input.CreateKeyEvent(Event.KeyboardEvent(eventKey));

Can be fixed by adding the following lines in front of line above

if (eventKey.Length == 1) {
    return;
}