Fix alert after the user is logged

If the user enters the wrong password the first time and then login, he
will be prompted with an error.
This commit fixes this behaviour.

frontend/js/actions/users.js

@@ -1,6 +1,6 @@
 import { configureAxios, request } from "../requests"
 
-import { addAlertOk } from "./alerts"
+import { addAlertOk, dismissAlert } from "./alerts"
 
 import { getManagedPolochons } from "./polochon"
 
@@ -20,6 +20,9 @@ export function loginUser(username, password) {
         password: password,
       },
     ),
+    [
+      () => dismissAlert(),
+    ]
   )
 }