fix(sdk): Polish the downloader/manager package error return

Close #8471

Signed-off-by: Dong Gang <dong.gang@daocloud.io>

cmd/helm/dependency_build.go

@@ -19,7 +19,9 @@ import (
 	"io"
 	"os"
 	"path/filepath"
+	"strings"
 
+	"github.com/pkg/errors"
 	"github.com/spf13/cobra"
 	"k8s.io/client-go/util/homedir"
 
@@ -65,7 +67,11 @@ func newDependencyBuildCmd(out io.Writer) *cobra.Command {
 			if client.Verify {
 				man.Verify = downloader.VerifyIfPossible
 			}
-			return man.Build()
+			err := man.Build()
+			if e, ok := err.(downloader.ErrRepoNotFound); ok {
+				return errors.Errorf("no repository definition for %s. Please add the missing repos via 'helm repo add'", strings.Join(e.Repos, ", "))
+			}
+			return err
 		},
 	}
 

pkg/downloader/manager.go

@@ -42,6 +42,16 @@ import (
 	"helm.sh/helm/v3/pkg/repo"
 )
 
+// ErrRepoNotFound indicates that chart repositories can't be found in local repo cache.
+// The value of Repos is missing repos.
+type ErrRepoNotFound struct {
+	Repos []string
+}
+
+func (e ErrRepoNotFound) Error() string {
+	return fmt.Sprintf("no repository definition for %s", strings.Join(e.Repos, ", "))
+}
+
 // Manager handles the lifecycle of fetching, resolving, and storing dependencies.
 type Manager struct {
 	// Out is used to print warnings and notifications.
@@ -411,7 +421,7 @@ Loop:
 		missing = append(missing, dd.Repository)
 	}
 	if len(missing) > 0 {
-		return errors.Errorf("no repository definition for %s. Please add the missing repos via 'helm repo add'", strings.Join(missing, ", "))
+		return ErrRepoNotFound{missing}
 	}
 	return nil
 }