NextJs firebase auth , Fab build error

[Rashmi-278]

Attempting to deploy this to cloudflare workers using fab https://github.com/vercel/next.js/tree/canary/examples/with-firebase-authentication

npm run build success
npx fab build fails

Build failed.
null
./.fab/.cache/generated-nextjs-renderers.266d5ec.js 152103:17
Module parse failed: Assigning to rvalue (152103:17)
You may need an appropriate loader to handle this file type, currently no loaders are configured to process this file. See https://webpack.js.org/concepts#loaders
(Source code omitted for this binary file)
 @ ./.fab/.cache/entry-point.js 2:22-146
    TypeError: Cannot read property 'message' of undefined

Tried downgrading next@10.0.3 to next@9.5.5
That didn't work ,

I couldn't find a solution for the error
Module parse failed: Assigning to rvalue (152103:17)
You may need an appropriate loader to handle this file type, currently no loaders are configured to process this file. See https://webpack.js.org/concepts#loaders
(Source code omitted for this binary file)

Any suggestions on which loader should I be using along with Webpack to make fab build a success ?