Electron packager built app not fully executable (Darwin/Mac Build) - macos

Question

I've built an electron app which is only executable if I directly execute the file (double click or via Terminal) locates at MyApp.app/Contents/MacOs/MyApp.
When I click the app MyApp.app directly via Finder electron window appears but only with an empty window. The backend isn't starting and so no frotend appears. The dificult thing here actually is that there isn't any logging/error message(s) that help me to understand whats not working here.
The App is built using this command:
electron-packager --asar . MyApp --ignore='^/build' --platform=darwin --arch=x64 --overwrite
Inside the electron app (simplified) I start an express server beside the main electron process:
// The express application
require(path.join(__dirname + "/bundle/dist/server"));
// Standard electron scaffolding
const createWindow = () => {
const win = new BrowserWindow({
width: 800,
height: 600,
webPreferences: {
preload: path.join(__dirname, "scripts/preload.js"),
},
});
setTimeout(() => {
win.loadURL("http://localhost:1234");
}, 1000);
};
Can someone maybe give me an advice why it's only starting when going the way via Package content and not directly by clicking the app icon?