fix(tracking): only resolve signup product when callbackPath was explicitly provided (#1793)

* fix(tracking): only resolve signup product when callbackPath was explicitly provided

* style: apply oxfmt formatting to after-sign-in route

Author: pedroheyerdahl

src/app/users/after-sign-in/route.tsx

@@ -49,7 +49,10 @@ export async function GET(request: NextRequest) {
       // callbackPath query param, so the value cannot be user-tampered. This
       // runs exactly once per signup because has_validation_stytch is set
       // after account verification completes.
-      const product = resolveSignupProduct(responsePath, !!url.searchParams.get('source'));
+      const product = resolveSignupProduct(
+        callbackPath && isValidCallbackPath(callbackPath) ? responsePath : null,
+        !!url.searchParams.get('source')
+      );
       if (product) {
         PostHogClient().capture({
           distinctId: user.google_user_email,