chore: improve error handling

pkg/querier/vcs/client/github.go

@@ -82,3 +82,20 @@ func toString(s *string) string {
 	}
 	return *s
 }
+
+func MapErrorToConnectCode(err error) error {
+	var githubErr *github.ErrorResponse
+	if errors.As(err, &githubErr) {
+		switch githubErr.Response.StatusCode {
+		case http.StatusNotFound:
+			return connect.NewError(connect.CodeNotFound, err)
+		case http.StatusForbidden:
+			return connect.NewError(connect.CodePermissionDenied, err)
+		case http.StatusUnauthorized:
+			return connect.NewError(connect.CodeUnauthenticated, err)
+		case http.StatusTooManyRequests:
+			return connect.NewError(connect.CodeResourceExhausted, err)
+		}
+	}
+	return connect.NewError(connect.CodeUnknown, err)
+}

pkg/querier/vcs/service.go

@@ -199,7 +199,7 @@ func (q *Service) GetCommit(ctx context.Context, req *connect.Request[vcsv1.GetC
 
 	commit, err := q.tryGetCommit(ctx, ghClient, owner, repo, ref)
 	if err != nil {
-		return nil, connect.NewError(connect.CodeNotFound, fmt.Errorf("failed to get commit: %v", err))
+		return nil, client.MapErrorToConnectCode(err)
 	}
 
 	return connect.NewResponse(commit), nil
@@ -214,16 +214,18 @@ func (q *Service) tryGetCommit(ctx context.Context, client gitHubCommitGetter, o
 		"tags/" + ref,  // Try as a tag
 	}
 
+	var lastErr error
 	for _, format := range refFormats {
 		commit, err := client.GetCommit(ctx, owner, repo, format)
 		if err == nil {
 			return commit, nil
 		}
 
-		q.logger.Log("err", err, "msg", "Failed to get commit", "ref", format)
+		lastErr = err
+		q.logger.Log("err", lastErr, "msg", "Failed to get commit", "ref", format)
 	}
 
-	return nil, fmt.Errorf("no commit found for %s/%s", owner, repo)
+	return nil, lastErr
 }
 
 func rejectExpiredToken(token *oauth2.Token) error {

pkg/querier/vcs/service_test.go

@@ -2,9 +2,12 @@ package vcs
 
 import (
 	"context"
+	"errors"
+	"net/http"
 	"testing"
 
 	"github.com/go-kit/log"
+	"github.com/google/go-github/v58/github"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/mock"
 
@@ -69,10 +72,13 @@ func TestTryGetCommit(t *testing.T) {
 			wantErr:    false,
 		},
 		{
-			name: "Nonexistent reference",
+			name: "GitHub API returns not found error",
 			setupMock: func(m *gitHubCommitGetterMock) {
+				notFoundErr := &github.ErrorResponse{
+					Response: &http.Response{StatusCode: http.StatusNotFound},
+				}
 				m.On("GetCommit", mock.Anything, mock.Anything, mock.Anything, mock.Anything).
-					Return(nil, assert.AnError).Times(3)
+					Return(nil, notFoundErr).Times(3)
 			},
 			ref:        "nonexistent",
 			wantCommit: nil,
@@ -89,6 +95,8 @@ func TestTryGetCommit(t *testing.T) {
 
 			if tt.wantErr {
 				assert.Error(t, err)
+				var githubErr *github.ErrorResponse
+				assert.True(t, errors.As(err, &githubErr), "Expected a GitHub error")
 			} else {
 				assert.NoError(t, err)
 			}