[Python] API Connection doesnt recognize correct function

I have this Code just to try if my api works and to implement a useful function later:

from flask import Flask, jsonify
from flask_cors import CORS
import mysql.connector
import pandas as pd
import io
import json

app = Flask(__name__)
CORS(app)




@app.route('/contacts')
def index():
return jsonify({'message': 'API läuft', 'route': '/contacts'})

db = mysql.connector.connect(
host = "localhost",
user = "root",
password = "******",
database = "******"
)
if __name__ == "__main__":
app.run(Debug = True)


in the console i get the path to the current api and direct to /contacts to call on the api and get: TypeError

TypeError: The view function for 'index' did not return a valid response. The function either returned None or ended without a return statement.

i already tried to implement it without jsonify but same result. also tried it without the database connection incase it fails. Other posts suggested a function that return none but i dont have that. this is the current entire code

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