fix: vercel url

Author: shadcn

env.mjs

@@ -21,7 +21,7 @@ export const env = createEnv({
     NEXT_PUBLIC_APP_URL: z.string().min(1),
   },
   runtimeEnv: {
-    NEXTAUTH_URL: process.env.NEXTAUTH_URL || process.env.VERCEL_URL,
+    NEXTAUTH_URL: process.env.VERCEL_URL ?? process.env.NEXTAUTH_URL,
     NEXTAUTH_SECRET: process.env.NEXTAUTH_SECRET,
     GITHUB_CLIENT_ID: process.env.GITHUB_CLIENT_ID,
     GITHUB_CLIENT_SECRET: process.env.GITHUB_CLIENT_SECRET,