fix(server/flash): Api to match documentation

This fixes duplication issues and normalize our use with everyone else

server/middlewares/error-handlers.js

@@ -79,10 +79,7 @@ export default function prodErrorHandler() {
         );
       }
       if (typeof req.flash === 'function') {
-        req.flash(
-          handled.type || 'danger',
-          { msg: message }
-        );
+        req.flash(handled.type || 'danger', message);
       }
       return res.redirect(redirectTo);
       // json