chore: use process.env.VERCEL to detect Vercel

Author: balazsorban44

src/jwt/index.ts

@@ -71,7 +71,7 @@ export async function getToken<R extends boolean = false>(
   const {
     req,
     secureCookie = process.env.NEXTAUTH_URL?.startsWith("https://") ??
-      !!process.env.VERCEL_URL,
+      !!process.env.VERCEL,
     cookieName = secureCookie
       ? "__Secure-next-auth.session-token"
       : "next-auth.session-token",

src/lib/types.ts

@@ -50,7 +50,7 @@ export type NextAuthAction =
 export interface InternalOptions<T extends ProviderType = any> {
   providers: InternalProvider[]
   /**
-   * Parsed from `NEXTAUTH_URL` or `VERCEL_URL`.
+   * Parsed from `NEXTAUTH_URL` or `x-forwarded-host` on Vercel.
    * @default "http://localhost:3000/api/auth"
    */
   url: InternalUrl

src/next/utils.ts

@@ -17,7 +17,7 @@ export function setCookie(res, cookie: Cookie) {
 /** Extract the host from the environment */
 export function detectHost(forwardedHost: any) {
   // If we detect a Vercel environment, we can trust the host
-  if (process.env.VERCEL === "1") return forwardedHost
+  if (process.env.VERCEL) return forwardedHost
   // If `NEXTAUTH_URL` is `undefined` we fall back to "http://localhost:3000"
   return process.env.NEXTAUTH_URL
 }