In my case this issue was caused because I started using webpack/vite bundlers for my existing firebase project. Initially 'firebase deploy' was mapped to the 'build' folder and I had to change it to 'dist' folder in 'firebase.json'. Else 'firebase deploy' kept deploying my old builds which had code that relied on deps that I already had uninstalled. Which somehow gave me the blank page with 'process is not defined' error.