Temporarily rescue Module::DelegationError in worker

Groups::ExportMembershipsWorker is currently raising
Module::DelegationError in circumstances where User records are
unavailable. That is causing these workers to fail and be re-tried,
only to fail again. To avoid this impact on infrastructure while we
troubleshoot the bug, this adds a temporary rescue clause to the
worker. This clause will be removed when the bug is fixed in a
follow-up.

ee/app/workers/groups/export_memberships_worker.rb

@@ -16,6 +16,10 @@ module Groups
       @response = Groups::Memberships::ExportService.new(container: @group, current_user: @current_user).execute
 
       send_email if @response.success?
+    rescue Module::DelegationError => exception
+      # TEMPORARY: Rescue when a User record is not available,
+      # see https://gitlab.com/gitlab-org/gitlab/-/issues/338707
+      Raven.capture_exception(exception, group_id: @group.id, user_id: @current_user.id)
     end
 
     private

ee/spec/workers/groups/export_memberships_worker_spec.rb

@@ -19,4 +19,18 @@ RSpec.describe Groups::ExportMembershipsWorker do
 
     worker.perform(group.id, user.id)
   end
+
+  context 'when there is a Module::DelegationError' do
+    before do
+      allow_next_instance_of(Groups::Memberships::ExportService) do |service|
+        allow(service).to receive(:execute).and_raise(Module::DelegationError)
+      end
+    end
+
+    it 'rescues the exception' do
+      expect(Notify).not_to receive(:memberships_export_email)
+      expect(Raven).to receive(:capture_exception)
+      worker.perform(group.id, user.id)
+    end
+  end
 end