Enhance handling of 'next' path in auth callback

This update improves the logic for handling the 'next' path in the auth callback service. Now, it first checks the query parameters for the 'next' path. If it's not found there, it looks into the callback URL

packages/supabase/src/auth-callback.service.ts

@@ -49,9 +49,24 @@ class AuthCallbackService {
     const token_hash = searchParams.get('token_hash');
     const type = searchParams.get('type') as EmailOtpType | null;
     const callbackParam = searchParams.get('callback');
+    const nextParam = searchParams.get('next');
 
+    let nextPath: string | null = null;
     const callbackUrl = callbackParam ? new URL(callbackParam) : null;
-    const nextPath = callbackUrl ? callbackUrl.searchParams.get('next') : null;
+
+    // if we have a next path in the query params, we use that
+    if (nextParam) {
+      nextPath = nextParam;
+    } else {
+      // if we have a callback url, we check if it has a next path
+      const callbackNextPath = callbackUrl ? callbackUrl.searchParams.get('next') : null;
+
+      // if we have a next path in the callback url, we use that
+      if (callbackNextPath) {
+        nextPath = callbackNextPath;
+      }
+    }
+
     const inviteToken = callbackUrl?.searchParams.get('invite_token');
     const errorPath = params.errorPath ?? '/auth/callback/error';