Troubleshooting
When developing electron apps there are two processes: main, and renderer.  In this case main corresponds to electron-starter.js and its console is wherever you called npm run dev or electron . from. renderer corresponds to the React App - this is everything else. The react app's console is in the electron/browser window and can be seen by using dev tools to inspect the window.  When running npm run dev, it should open by default.
Potential Issues
Package not found or other error related to npm
Try deleting your node_modules folder and the package-lock.json then running npm install then npm run rebuild.
Inspecting Errors
In case you want to find out where the error is coming from when running the app locally:
- Try reviewing logs in the terminal
 - Inspect element in your browser by openning your developer tools. For instance, in Chrome, this can be done via the menu View -> Developer or right-clicking and pressing inspect.