enable errorlint linter

.golangci.yaml

@@ -289,6 +289,7 @@ linters:
     - bodyclose
     - depguard
     - errcheck
+    - errorlint
     - exportloopref
     - funlen
     - gci

cmd/helm3.go

@@ -25,7 +25,7 @@ func getHelmVersion() (*semver.Version, error) {
 	debugPrint("Executing %s", strings.Join(cmd.Args, " "))
 	output, err := cmd.CombinedOutput()
 	if err != nil {
-		return nil, fmt.Errorf("Failed to run `%s version`: %v", os.Getenv("HELM_BIN"), err)
+		return nil, fmt.Errorf("Failed to run `%s version`: %w", os.Getenv("HELM_BIN"), err)
 	}
 	versionOutput := string(output)
 
@@ -35,7 +35,7 @@ func getHelmVersion() (*semver.Version, error) {
 	}
 	helmVersion, err := semver.NewVersion(matches[1])
 	if err != nil {
-		return nil, fmt.Errorf("Failed to parse version %#v: %v", matches[1], err)
+		return nil, fmt.Errorf("Failed to parse version %#v: %w", matches[1], err)
 	}
 
 	return helmVersion, nil

cmd/helpers.go

@@ -1,6 +1,7 @@
 package cmd
 
 import (
+	"errors"
 	"fmt"
 	"os"
 	"os/exec"
@@ -32,7 +33,8 @@ func debugPrint(format string, a ...interface{}) {
 func outputWithRichError(cmd *exec.Cmd) ([]byte, error) {
 	debugPrint("Executing %s", strings.Join(cmd.Args, " "))
 	output, err := cmd.Output()
-	if exitError, ok := err.(*exec.ExitError); ok {
+	var exitError *exec.ExitError
+	if errors.As(err, &exitError) {
 		return output, fmt.Errorf("%s: %s", exitError.Error(), string(exitError.Stderr))
 	}
 	return output, err

cmd/upgrade.go

@@ -288,12 +288,12 @@ func (d *diffCmd) runHelm3() error {
 		}
 	}
 	if err != nil {
-		return fmt.Errorf("Failed to get release %s in namespace %s: %s", d.release, d.namespace, err)
+		return fmt.Errorf("Failed to get release %s in namespace %s: %w", d.release, d.namespace, err)
 	}
 
 	installManifest, err := d.template(!newInstall)
 	if err != nil {
-		return fmt.Errorf("Failed to render chart: %s", err)
+		return fmt.Errorf("Failed to render chart: %w", err)
 	}
 
 	if d.threeWayMerge {

main.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"errors"
 	"os"
 
 	_ "k8s.io/client-go/plugin/pkg/client/auth/azure"
@@ -13,9 +14,10 @@ import (
 
 func main() {
 	if err := cmd.New().Execute(); err != nil {
-		switch e := err.(type) {
-		case cmd.Error:
-			os.Exit(e.Code)
+		var cmdErr cmd.Error
+		switch {
+		case errors.As(err, &cmdErr):
+			os.Exit(cmdErr.Code)
 		default:
 			os.Exit(1)
 		}

manifest/parse.go

@@ -134,7 +134,7 @@ func parseContent(content string, defaultNamespace string, normalizeManifests bo
 
 			subs, err := parseContent(string(subcontent), defaultNamespace, normalizeManifests, excludedHooks...)
 			if err != nil {
-				return nil, fmt.Errorf("Parsing YAML list item: %v", err)
+				return nil, fmt.Errorf("Parsing YAML list item: %w", err)
 			}
 
 			result = append(result, subs...)