In Electron, the process that runs package.json’s main script is called the main process. The script that runs in the main process can display a GUI by creating web pages.
From the Electron Documentation
Since the main process is essentially a full node environment, there is no initial project structure other than two files.
This file is you app's main file, the file in which electron boots with, and is also used as webpack's entry file. All main process development should start from here.
This file is used specifically and only for development. It enables the use of ES6+ features for the main process and installs electron-debug & vue-devtools. There shouldn't be any need to modify this file, but it can be used to extend your development environment.
Since the main process is bundled using webpack, the use of __dirname & __filename will not provide an expected value in production.
Referring to Project Structure, you'll notice that in production the main.js is placed inside the dist folder. Based on this knowledge, use __dirname & __filename accordingly.
app.asar
├─ dist
│ ├─ main.js
│ ├─ renderer.js
│ └─ index.html
└─ node_modules/
└─ package.json