[Sync] Fix crash while updating subscriptions for invalidations

The list of subscriptions may be updated when sync engine is not
initialized.

Bug: 1318023
Change-Id: I7448596076a09d046ac17d746e3bbd778cee4ad5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3596150
Auto-Submit: Rushan Suleymanov <rushans@google.com>
Commit-Queue: Rushan Suleymanov <rushans@google.com>
Reviewed-by: Marc Treib <treib@chromium.org>
Commit-Queue: Marc Treib <treib@chromium.org>
Cr-Commit-Position: refs/heads/main@{#994177}

components/sync/driver/sync_service_impl.cc

@@ -1237,7 +1237,8 @@ void SyncServiceImpl::UpdateDataTypesForInvalidations() {
 
   // Wait for configuring data types. This is needed to consider proxy types
   // which become known during configuration.
-  if (data_type_manager_->state() != DataTypeManager::CONFIGURED) {
+  if (!data_type_manager_ ||
+      data_type_manager_->state() != DataTypeManager::CONFIGURED) {
     return;
   }