Missed argument for parameter one in Javascript (Momiji)

Hi,

I'm getting an inspection warning but I can't spot a problem with it:

  $('#user_email').on('change', function() {
    $(this).val($(this).val().replace(/@domain1/gi, '@domain2'))
  });

Missed argument for parameter one

I was going to submit it to the bug tracker but then I figured it's probably me just not seeing my error. Screenshot attached.

If another pair of eyes could take a look I'd be grateful.