ref(helm): Export Chart Not Found error

Closes #30746

Signed-off-by: Stephen Murray <stephenmurrayengineer@gmail.com>

pkg/repo/chartrepo.go

@@ -219,7 +219,10 @@ func FindChartInRepoURL(repoURL string, chartName string, getters getter.Provide
 	}
 	cv, err := repoIndex.Get(chartName, opts.ChartVersion)
 	if err != nil {
-		return "", errors.Errorf("%s not found in %s repository", errMsg, repoURL)
+		return "", ChartNotFoundError{
+			Chart:   errMsg,
+			RepoURL: repoURL,
+		}
 	}
 
 	if len(cv.URLs) == 0 {

pkg/repo/chartrepo_test.go

@@ -18,6 +18,7 @@ package repo
 
 import (
 	"bytes"
+	"errors"
 	"net/http"
 	"net/http/httptest"
 	"os"
@@ -202,6 +203,9 @@ func TestErrorFindChartInRepoURL(t *testing.T) {
 	} else if err.Error() != `chart "nginx1" not found in `+srv.URL+` repository` {
 		t.Errorf("Expected error for chart not found, but got a different error (%v)", err)
 	}
+	if !errors.Is(err, ChartNotFoundError{}) {
+		t.Errorf("error is not of correct error type structure")
+	}
 
 	if _, err = FindChartInRepoURL(srv.URL, "nginx1", g, WithChartVersion("0.1.0")); err == nil {
 		t.Errorf("Expected error for chart not found, but did not get any errors")

pkg/repo/error.go

@@ -0,0 +1,35 @@
+/*
+Copyright The Helm Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package repo
+
+import (
+	"fmt"
+)
+
+type ChartNotFoundError struct {
+	RepoURL string
+	Chart   string
+}
+
+func (e ChartNotFoundError) Error() string {
+	return fmt.Sprintf("%s not found in %s repository", e.Chart, e.RepoURL)
+}
+
+func (e ChartNotFoundError) Is(err error) bool {
+	_, ok := err.(ChartNotFoundError)
+	return ok
+}