ErrWut is a simple addon for easily enabling and disabling error messages and sounds in macros.
ErrWut adds a command /err, which accepts 'on' to enable errors messages, and 'off' to disable them; no command given will toggle between the two.
ErrWut is currently simple and primitive, so it won't respect your settings; if you run /err on it will force error sounds on, even if they weren't enabled beforehand. ErrWut is also totally untested, but it's simple enough that I trust it's bug free, simply by the look of its code.