add user check in auth-with-stytch. (#38648)

* add user check in `auth-with-stytch`.

* Revert "delete auto.js in pollyfills"

* lint-fix

Co-authored-by: JJ Kasper <jj@jjsweb.site>

examples/auth-with-stytch/pages/index.tsx

@@ -48,13 +48,17 @@ const stytchProps: StytchProps = {
   },
   publicToken: process.env.NEXT_PUBLIC_STYTCH_PUBLIC_TOKEN || '',
   callbacks: {
-    onEvent: (data) => {
-      // TODO: check whether the user exists in your DB
-      if (data.eventData.type === 'USER_EVENT_TYPE') {
+    onEvent: (data: { eventData: { userId: any; email: any } }) => {
+      if (
+        data.eventData.userId !== undefined &&
+        data.eventData.userId != null
+      ) {
         console.log({
           userId: data.eventData.userId,
           email: data.eventData.email,
         })
+      } else {
+        console.warn('The user is not found. Data: ', data)
       }
     },
     onSuccess: (data) => console.log(data),