Fix: Server crashed when logging in with wrong credentials

app.js

@@ -79,7 +79,7 @@ app.get('/login', (req, res) => {
 
     con.query("SELECT PASSWORT, USERNAME FROM ministranten WHERE (USERNAME='" + id + "' OR EMAIL='" + id + "')", (err, result) => {
         if (err) throw err;
-        if(password == result[0]["PASSWORT"]){
+        if(result[0] != null && password == result[0]["PASSWORT"]){
             var usertoken = uuid();
             res.cookie("loginToken", usertoken);
             res.cookie("user", result[0]["USERNAME"]);