Fix newError noops when not bound to dispacher (#4013)

* AddContract properly binds newError

* EditMeta properly binds newError

* PasswordManager properly binds newError

* pass null instead of empty mapStateToProps

* Add openSnackbar test & binded prop

js/src/redux/providers/snackbarActions.js

@@ -20,7 +20,7 @@ export function showSnackbar (message, cooldown) {
   };
 }
 
-function openSnackbar (message, cooldown) {
+export function openSnackbar (message, cooldown) {
   return {
     type: 'openSnackbar',
     message, cooldown