Fix undefined method pending_delete for nil class

ee/app/workers/geo/repository_verification/secondary/single_worker.rb

@@ -18,7 +18,7 @@ module Geo
           return unless Gitlab::Geo.secondary?
 
           @registry = Geo::ProjectRegistry.find_by_id(registry_id)
-          return if registry.nil? || project.pending_delete?
+          return if registry.nil? || project.nil? || project.pending_delete?
 
           try_obtain_lease do
             verify_checksum(:repository)

ee/spec/workers/geo/repository_verification/secondary/single_worker_spec.rb

@@ -36,6 +36,12 @@ describe Geo::RepositoryVerification::Secondary::SingleWorker, :postgresql, :cle
       expect { subject.perform(-1) }.not_to raise_error
     end
 
+    it 'does not raise an error when project could not be found' do
+      registry.update_column(:project_id, -1)
+
+      expect { subject.perform(registry.id) }.not_to raise_error
+    end
+
     it 'runs verification for both repository and wiki' do
       create(:repository_state, project: project, repository_verification_checksum: 'my_checksum', wiki_verification_checksum: 'my_checksum')