rollbar.js

function ignoreThisMessage(isUncaught, args, payload) {
  var ignore = "Protocols, domains, and ports must match.";
  if (
    payload &&
    payload.body &&
    payload.body.message &&
    payload.body.message.body &&
    !!~payload.body.message.body.indexOf(ignore)
  ) {
    return true
  };
}
if (Rollbar) Rollbar.configure({checkIgnore: ignoreThisMessage});

This will fail if Rollbar doesn't load. You can't check existence of a variable that was never set.