fix: improve new-action-cache fetch failure error (#2172)

- include repoURL and repoRef in error
- map NoErrAlreadyUptodate to `couldn't find remote ref` for branchOrtag
  fetch request

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

pkg/runner/action_cache.go

@@ -6,6 +6,7 @@ import (
 	"crypto/rand"
 	"encoding/hex"
 	"errors"
+	"fmt"
 	"io"
 	"io/fs"
 	"path"
@@ -86,6 +87,9 @@ func (c GoGitActionCache) Fetch(ctx context.Context, cacheDir, url, ref, token s
 		Auth:  auth,
 		Force: true,
 	}); err != nil {
+		if tagOrSha && errors.Is(err, git.NoErrAlreadyUpToDate) {
+			return "", fmt.Errorf("couldn't find remote ref \"%s\"", ref)
+		}
 		return "", err
 	}
 	if tagOrSha {

pkg/runner/step_action_remote.go

@@ -68,9 +68,11 @@ func (sar *stepActionRemote) prepareActionExecutor() common.Executor {
 
 			var err error
 			sar.cacheDir = fmt.Sprintf("%s/%s", sar.remoteAction.Org, sar.remoteAction.Repo)
-			sar.resolvedSha, err = cache.Fetch(ctx, sar.cacheDir, sar.remoteAction.URL+"/"+sar.cacheDir, sar.remoteAction.Ref, github.Token)
+			repoURL := sar.remoteAction.URL + "/" + sar.cacheDir
+			repoRef := sar.remoteAction.Ref
+			sar.resolvedSha, err = cache.Fetch(ctx, sar.cacheDir, repoURL, repoRef, github.Token)
 			if err != nil {
-				return err
+				return fmt.Errorf("failed to fetch \"%s\" version \"%s\": %w", repoURL, repoRef, err)
 			}
 
 			remoteReader := func(ctx context.Context) actionYamlReader {