Error when deploying to Versel

[oleg-direct]

Describe the bug
Cloned example: https://github.com/gladly-team/next-firebase-auth/tree/v1.x/example

Configured local ENV var's & have not changed code, everything working on localhost as expected.
Run build locally & building with no problem

Versions

next-firebase-auth version:
Firebase JS SDK: 9.9.1
Next.js: 12.2.3

To Reproduce
Steps to reproduce the behavior:
Deploy project to versel

Getting following error:
`

yarn run v1.22.17

17:43:08.054 | $ next build
17:43:08.609 | Attention: Next.js now collects completely anonymous telemetry regarding usage.
17:43:08.610 | This information is used to shape Next.js' roadmap and prioritize features.
17:43:08.610 | You can learn more, including how to opt-out if you'd not like to participate in this anonymous program, by visiting the following URL:
17:43:08.610 | https://nextjs.org/telemetry
17:43:08.610 |  
17:43:08.774 | info - Linting and checking validity of types...
17:43:09.060 | warn - No ESLint configuration detected. Run next lint to begin setup
17:43:11.932 | info - Creating an optimized production build...
17:43:12.736 | Browserslist: caniuse-lite is outdated. Please run:
17:43:12.736 | npx browserslist@latest --update-db
17:43:12.737 | Why you should do it regularly: https://github.com/browserslist/browserslist#browsers-data-updating
17:43:18.181 | Browserslist: caniuse-lite is outdated. Please run:
17:43:18.181 | npx browserslist@latest --update-db
17:43:18.182 | Why you should do it regularly: https://github.com/browserslist/browserslist#browsers-data-updating
17:43:26.271 | info - Compiled successfully
17:43:26.272 | info - Collecting page data...
17:43:26.799 | node:internal/process/promises:288
17:43:26.799 | triggerUncaughtException(err, true /* fromPromise */);
17:43:26.799 | ^
17:43:26.800 |  
17:43:26.800 | SyntaxError: Unexpected number in JSON at position 1
17:43:26.800 | at JSON.parse ()
17:43:26.801 | at initAuth (/vercel/path0/.next/server/pages/_app.js:83:69)
17:43:26.801 | at 5672 (/vercel/path0/.next/server/pages/_app.js:116:1)
17:43:26.801 | at webpack_require (/vercel/path0/.next/server/webpack-runtime.js:25:42)
17:43:26.803 | at webpack_exec (/vercel/path0/.next/server/pages/_app.js:153:39)
17:43:26.807 | at /vercel/path0/.next/server/pages/_app.js:154:28
17:43:26.807 | at Object. (/vercel/path0/.next/server/pages/_app.js:157:3)
17:43:26.808 | at Module._compile (node:internal/modules/cjs/loader:1218:14)
17:43:26.808 | at Module._extensions..js (node:internal/modules/cjs/loader:1272:10)
17:43:26.808 | at Module.load (node:internal/modules/cjs/loader:1081:32) {
17:43:26.809 | type: 'SyntaxError'
17:43:26.809 | }
17:43:26.809 |  
17:43:26.809 | Node.js v18.13.0
17:43:26.875 | error Command failed with exit code 1.
17:43:26.876 | info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.
17:43:26.921 | Error: Command "yarn run build" exited with 1
17:43:27.180 | BUILD_FAILED: Command "yarn run build" exited with 1

`

[oleg-direct]

Solved by adding "" to FIREBASE_PRIVATE_KEY

vercel/vercel#749 (comment)