v2: fix resolution of revalidation requests (#2926)

Author: SamyPesse

packages/gitbook-v2/src/lib/env.ts

@@ -4,8 +4,8 @@
 export const GITBOOK_URL =
     process.env.NODE_ENV === 'development'
         ? 'http://localhost:3000'
-        : ((process.env.VERCEL_URL ? `https://${process.env.VERCEL_URL}` : undefined) ??
-          process.env.GITBOOK_URL ??
+        : (process.env.GITBOOK_URL ??
+          (process.env.VERCEL_URL ? `https://${process.env.VERCEL_URL}` : undefined) ??
           '');
 
 /**

packages/gitbook-v2/src/middleware.ts

@@ -176,6 +176,9 @@ function extractURL(request: NextRequest): URLWithMode | null {
     // The x-forwarded-host is set by Vercel for all requests
     // so we ignore it if the hostname is the same as the instance one.
     if (xForwardedHost && GITBOOK_URL && new URL(GITBOOK_URL).host !== xForwardedHost) {
+        console.log('xForwardedHost', xForwardedHost, GITBOOK_URL, new URL(GITBOOK_URL).host);
+        console.log('process.env.VERCEL_URL', process.env.VERCEL_URL);
+        console.log('process.env.GITBOOK_URL', process.env.GITBOOK_URL);
         return {
             url: appendQueryParams(
                 new URL(`https://${xForwardedHost}${request.nextUrl.pathname}`),