Fix reading Component.__N_SSG (#10037)

* Fix error when reading Component.__NEXT_SPR in packages/next/client/index.js

* Use the .? optional chaining operator

Co-Authored-By: Tim Neutkens <tim@timneutkens.nl>

* Update index.js

Co-authored-by: Tim Neutkens <tim@timneutkens.nl>
Co-authored-by: Joe Haddad <timer150@gmail.com>

packages/next/client/index.js

@@ -94,7 +94,7 @@ class Container extends React.Component {
     if (
       (data.nextExport &&
         (isDynamicRoute(router.pathname) || location.search)) ||
-      (Component.__N_SSG && location.search)
+      (Component && Component.__N_SSG && location.search)
     ) {
       // update query on mount for exported pages
       router.replace(