Solved

@quasar/app-webpack 3.11.3

Quasar App (quasar-webpack-electron-test)

Quasar/Webpack 3.11.1 > 3.11.2 build error Electron

https://stackblitz.com/edit/jf-quasar-webpack-electron3-11-2

Working

package.json
  "@quasar/app-webpack": "3.11.1",

npm install
quasar dev -m electron \\ --> Working
quasar dev \\ --> Working

Error Electron build

package.json
  "@quasar/app-webpack": "^3.11.2",

npm install
quasar dev -m electron \\--> Build error
quasar dev \\ --> Working

Seems to have to do with modification:

https://github.com/quasarframework/quasar/commit/b4ce74000eecddd28cbaef956181ab5437e478be