Allow activate mutation to handle connection error

Rescue and return connection error message

ee/lib/gitlab/subscription_portal/clients/graphql.rb

@@ -44,6 +44,9 @@ module Gitlab
             else
               error(response['errors'])
             end
+          rescue Gitlab::HTTP::BlockedUrlError, HTTParty::Error, Errno::ECONNREFUSED, Errno::ECONNRESET, SocketError, Timeout::Error => e
+            Gitlab::ErrorTracking.log_exception(e)
+            error(CONNECTIVITY_ERROR)
           end
 
           def plan_upgrade_offer(namespace_id)

ee/spec/lib/gitlab/subscription_portal/clients/graphql_spec.rb

@@ -50,13 +50,23 @@ RSpec.describe Gitlab::SubscriptionPortal::Clients::Graphql do
       expect(result).to eq({ errors: ["invalid activation code"], success: false })
     end
 
-    it 'returns connectivity error' do
+    it 'returns connectivity error when remote server returns error' do
       stub_request(:any, EE::SUBSCRIPTIONS_GRAPHQL_URL).to_return(status: [500, "Internal Server Error"])
 
       result = client.activate('activation_code_abc')
 
       expect(result).to eq({ errors: described_class::CONNECTIVITY_ERROR, success: false })
     end
+
+    it 'returns connectivity error when the remote server is unreachable' do
+      stub_request(:any, EE::SUBSCRIPTIONS_GRAPHQL_URL).to_timeout
+      allow(Gitlab::ErrorTracking).to receive(:log_exception)
+
+      result = client.activate('activation_code_abc')
+
+      expect(result).to eq({ errors: described_class::CONNECTIVITY_ERROR, success: false })
+      expect(Gitlab::ErrorTracking).to have_received(:log_exception).with(kind_of(Timeout::Error))
+    end
   end
 
   describe '#plan_upgrade_offer' do