ignore 404 on ListFiles call (#24)

pkg/checkmate/commenter.go

@@ -2,6 +2,8 @@ package checkmate
 
 import (
 	"context"
+	"errors"
+	"net/http"
 	"sort"
 	"strings"
 
@@ -138,6 +140,9 @@ func updateComment(ctx context.Context, action *githubactions.Action, cfg Config
 
 func listPullRequestFiles(ctx context.Context, pr pullrequest.Client) ([]string, error) {
 	files, err := pr.ListFiles(ctx, nil)
+	if isNotFoundError(err) {
+		return nil, nil
+	}
 	if err != nil {
 		return nil, err
 	}
@@ -161,3 +166,13 @@ func sorted(ss []string) []string {
 func join(s ...string) string {
 	return strings.Join(s[:len(s)-1], s[len(s)-1])
 }
+
+func isNotFoundError(err error) bool {
+	ghe := new(github.ErrorResponse)
+	if errors.As(err, &ghe) {
+		if ghe.Response.StatusCode == http.StatusNotFound {
+			return true
+		}
+	}
+	return false
+}

pkg/checkmate/commenter_test.go

@@ -65,6 +65,22 @@ func Test_commenter(t *testing.T) {
 		assert.NoError(t, err)
 	})
 
+	t.Run("IssueCommentHasNoFiles", func(t *testing.T) {
+		action, _ := setupAction("issue-comment.created")
+		ghMockAPI := mock.NewMockedHTTPClient(
+			mock.WithRequestMatchHandler(
+				mock.GetReposPullsFilesByOwnerByRepoByPullNumber,
+				http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
+					mock.WriteError(w, http.StatusNotFound, "Not Found")
+				}),
+			))
+
+		pr, err := pullrequest.NewClient(action, github.NewClient(ghMockAPI))
+		assert.NoError(t, err)
+		_, err = commenter(ctx, cfg, action, pr)
+		assert.NoError(t, err)
+	})
+
 	t.Run("MatchingFilesNoExistingComment", func(t *testing.T) {
 		action, _ := setupAction("pull-request.edited")
 		ghMockAPI := mock.NewMockedHTTPClient(