add githubError.Cause back after more analysis

Signed-off-by: James Sheppard <jgsheppa@protonmail.com>

cmd/helm/repo.go

@@ -20,6 +20,7 @@ import (
 	"io"
 	"os"
 
+	"github.com/pkg/errors"
 	"github.com/spf13/cobra"
 
 	"helm.sh/helm/v3/cmd/helm/require"
@@ -49,5 +50,5 @@ func newRepoCmd(out io.Writer) *cobra.Command {
 }
 
 func isNotExist(err error) bool {
-	return os.IsNotExist(err)
+	return os.IsNotExist(errors.Cause(err))
 }

pkg/downloader/chart_downloader.go

@@ -400,7 +400,7 @@ func (c *ChartDownloader) scanReposForURL(u string, rf *repo.File) (*repo.Entry,
 
 func loadRepoConfig(file string) (*repo.File, error) {
 	r, err := repo.LoadFile(file)
-	if err != nil && !os.IsNotExist(err) {
+	if err != nil && !os.IsNotExist(githubErrors.Cause(err)) {
 		return nil, err
 	}
 	return r, nil