fix: consider the case where deliveries can be an empty list

pkg/retry/retry.go

@@ -125,6 +125,12 @@ func (s *Server) handleRetry() http.Handler {
 				return
 			}
 
+			if len(deliveries) == 0 {
+				logger.InfoContext(ctx, "no deliveries from GitHub",
+					"cursor", cursor)
+				break
+			}
+
 			// in anticipation of the happy path, store the first event to advance the
 			// cursor
 			if firstCheckpoint == "" {

pkg/retry/retry_test.go

@@ -126,6 +126,21 @@ func TestHandleRetry(t *testing.T) {
 				listDeliveries: &listDeliveriesRes{err: errors.New("error")},
 			},
 		},
+		{
+			name:          "github_list_deliveries_empty",
+			expStatusCode: http.StatusAccepted,
+			expRespBody:   `{"status":"accepted"}`,
+			datastoreClientOverride: &MockDatastore{
+				retrieveCheckpointID: &retrieveCheckpointIDRes{res: "checkpoint-id"},
+			},
+			gcsLockClientOverride: &MockLock{
+				acquire: &acquireRes{},
+			},
+			githubOverride: &MockGitHub{
+				listDeliveries: &listDeliveriesRes{deliveries: []*github.HookDelivery{},
+					res: &github.Response{}},
+			},
+		},
 		{
 			name:          "github_redeliver_event_failure_big_query_entry_not_exists",
 			expStatusCode: http.StatusInternalServerError,