[Autofill Auth] Opting-out of FIDO authentication does not cause a crash.

On the settings page, if user opts-in, then opts-out through the toggle switch,
the browser crashes because a non-existing dialog is being attempted to close.

Bug: 949269
Change-Id: I10d50695db65976799510960ae3230b355b3f698
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1884829
Commit-Queue: Manas Verma <manasverma@google.com>
Commit-Queue: Jared Saul <jsaul@google.com>
Reviewed-by: Jared Saul <jsaul@google.com>
Cr-Commit-Position: refs/heads/master@{#710064}

components/autofill/core/browser/payments/credit_card_fido_authenticator.cc

@@ -340,8 +340,9 @@ void CreditCardFIDOAuthenticator::OnDidGetOptChangeResult(
          current_flow_ == FOLLOWUP_AFTER_CVC_AUTH_FLOW);
   // End the flow if the server responded with an error.
   if (result != AutofillClient::PaymentsRpcResult::SUCCESS) {
+    if (current_flow_ != OPT_OUT_FLOW)
+      autofill_client_->UpdateWebauthnOfferDialogWithError();
     current_flow_ = NONE_FLOW;
-    autofill_client_->UpdateWebauthnOfferDialogWithError();
     return;
   }