Well,
I’m using 1.7.2 and got same problem…

UnhandledPromiseRejectionWarning:   TypeError: bundler is not a function

  - index.js:137 Promise
    [my-app]/[@quasar]/app/lib/electron/index.js:137:13

  - new Promise

  - index.js:132 Promise.then.then
    [my-app]/[@quasar]/app/lib/electron/index.js:132:14

  - next_tick.js:68 process._tickCallback
    internal/process/next_tick.js:68:7

However quasar dev -m electron is working properly

So… 1.7.3 seems to fix this, but this is very weird…