Fix Vercel Deployment JavaScript Errors

My JavaScript-based website runs perfectly on localhost, but the moment I push it to Vercel the build breaks with a flood of syntax and other runtime errors. The logs also complain about Supabase database connections even though I already set every required environment variable in Vercel... (Budget: $10 - $30 USD, Jobs: Debugging, Frontend Development, Git, JavaScript, Node.js, PHP, Supabase, Vercel, Web Development, WordPress)