fix message

lib/env.ts

@@ -2,12 +2,8 @@ import { loadEnvConfig } from "@next/env";
 
 loadEnvConfig(process.cwd());
 
-function getRequiredEnv(name: string): string {
-  const value = process.env[name];
-  if (!value) {
-    throw new Error(`Missing required environment variable: ${name}`);
-  }
-  return value;
+function getRequiredEnv(name: string): string | null | undefined {
+  return process.env[name];
 }
 
 function getOptionalEnv(name: string): string | undefined {