Req: Send shell command button: show error if sh or su not found

[DrShark]

It would be nice it TС for "Send shell command" function type of button with sh or su command would show "<sh or su> file not found" error in case sh or su command doesn't exist on device. Currently a tap on "Send shell command" with su command not available doesn't indicate an error: nothing happens. (su command usually available only on rooted devices; sh exists on most devices and can probably disappear only in case of virus activity)