implemented brute force counter measure

frontend/src/user.svelte.js

@@ -43,8 +43,10 @@ export async function tryLogin(credentials){
     if (response.ok){
         const json = await response.json();
         for (let key of Object.keys(json)) user[key] = json[key];
-
+        return null;
     } else {
         alert("Login failed!");
+        let json = await response.json();
+        return json;
     }
 }