I had my App (mern stack, but this is just about the backend) running inside another directory where i had both frontend and backend running in the same folder. Today i splitted them up and put the backend stuff inside another folder to keep backend and frontend in different folders. After running yarn start:backend it does connect, and i get my message "server started at http://localhost:5000". However, instead of getting "mongoose connected", i get "undefined" and the routes doesent work.

I thought it might be because it does not find the env variables, but after inserting the if statement it shows the route to my db, so this cant be the reason.

server.mjs

import express from 'express';
import dotenv from 'dotenv';
import config from './config.mjs'
import mongoose  from 'mongoose';
import userRoute from './routes/userRoute.mjs';
import productRoute from './routes/productRoute.mjs';
import orderRouter from './routes/orderRouter.js';
import bodyParser from 'body-parser';
import cors from 'cors';

//load env context into dotenv
dotenv.config();

//middleware
const app=express();
app.use(cors());                              
app.use(bodyParser.json());                   
app.use(express.json());                       
app.use(express.urlencoded({extended: true}));

// error middleware
app.use((err, req, res, next)=> {
    res.status(500).send({ message: err.message});
})

if(config.mongodb_URL){console.log(config.mongodb_URL);}
else console.log("not found")


// MONGODB CONNECTION + Test
const mongodbUrl = config.mongodb_URL;
mongoose.connect(mongodbUrl,{
    useNewUrlParser: true,
    useUnifiedTopology: true,
    useCreateIndex: true
}).catch(error=>console.log(error.reason));

mongoose.connection.on('connected', ()=> {
    console.log('mongoose connected')
});




    //concat link
app.use("/api/users", userRoute);
app.use("/api/products", productRoute);
app.use("/api/orders", orderRouter);
app.get('/api/config/paypal', (req, res) => {
    res.send(process.env.PAYPAL_CLIENT_ID || 'sb');
})



app.listen(5000, ()=> {console.log("server started at http://localhost:5000")}); 

config.mjs

import dotenv from 'dotenv';
dotenv.config();

export default {
    mongodb_URL: process.env.MONGODB_URL || "",
    JWT_SECRET: process.env.JWT_SECRET || 'somethingsecret'
}

I really dont have a clue where i can search, because i dont have any errors inside the browser and no errors inside vscode.

What have i forget and what do you think where the error might be?