fix: prevent panic in helmfile init on plugin install errors (#2401)

toCLIError() panics on unhandled error types (e.g. helmexec.ExitError
from a failed helm plugin install). On Windows, plugin install hooks
often fail due to missing 'sh', causing helmfile init to crash even
when the plugin binary was placed correctly.

- Add helmexec.ExitError case to toCLIError and replace panic in the
  default case with a graceful error return
- After AddPlugin/UpdatePlugin errors, verify whether the plugin is
  actually present before failing; log a warning and continue if so

Fixes #1983

Signed-off-by: Aditya Menon <amenon@canarytechnologies.com>

cmd/root.go

@@ -1,6 +1,7 @@
 package cmd
 
 import (
+	stderrors "errors"
 	"fmt"
 	"os"
 
@@ -23,6 +24,10 @@ var globalUsage = "Declaratively deploy your Kubernetes manifests, Kustomize con
 
 func toCLIError(g *config.GlobalImpl, err error) error {
 	if err != nil {
+		var exitErr helmexec.ExitError
+		if stderrors.As(err, &exitErr) {
+			return errors.NewExitError(exitErr.Error(), exitErr.ExitStatus())
+		}
 		switch e := err.(type) {
 		case *app.NoMatchingHelmfileError:
 			noMatchingExitCode := 3
@@ -35,7 +40,7 @@ func toCLIError(g *config.GlobalImpl, err error) error {
 		case *app.Error:
 			return errors.NewExitError(e.Error(), e.Code())
 		default:
-			panic(fmt.Errorf("BUG: please file an github issue for this unhandled error: %T: %v", e, e))
+			return errors.NewExitError(fmt.Sprintf("unexpected error: %T: %v", e, e), 1)
 		}
 	}
 	return err

cmd/root_test.go

@@ -0,0 +1,72 @@
+package cmd
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"github.com/helmfile/helmfile/pkg/config"
+	"github.com/helmfile/helmfile/pkg/errors"
+	"github.com/helmfile/helmfile/pkg/helmexec"
+)
+
+func TestToCLIError(t *testing.T) {
+	g := config.NewGlobalImpl(&config.GlobalOptions{})
+
+	tests := []struct {
+		name            string
+		err             error
+		wantNil         bool
+		wantExitCode    int
+		wantMsgContains string
+	}{
+		{
+			name:    "nil error returns nil",
+			err:     nil,
+			wantNil: true,
+		},
+		{
+			name: "helmexec.ExitError returns correct exit code",
+			err: helmexec.ExitError{
+				Message: "helm command failed",
+				Code:    7,
+			},
+			wantExitCode:    7,
+			wantMsgContains: "helm command failed",
+		},
+		{
+			name:            "wrapped helmexec.ExitError preserves exit code",
+			err:             fmt.Errorf("helm version failed: %w", helmexec.ExitError{Message: "exit status 7", Code: 7}),
+			wantExitCode:    7,
+			wantMsgContains: "exit status 7",
+		},
+		{
+			name:            "unknown error type returns exit code 1 without panic",
+			err:             fmt.Errorf("some unexpected error"),
+			wantExitCode:    1,
+			wantMsgContains: "unexpected error",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			// Should never panic
+			var result error
+			assert.NotPanics(t, func() {
+				result = toCLIError(g, tt.err)
+			})
+
+			if tt.wantNil {
+				assert.NoError(t, result)
+				return
+			}
+
+			assert.Error(t, result)
+			exitErr, ok := result.(*errors.ExitError)
+			assert.True(t, ok, "expected *errors.ExitError, got %T", result)
+			assert.Equal(t, tt.wantExitCode, exitErr.ExitCode())
+			assert.Contains(t, exitErr.Error(), tt.wantMsgContains)
+		})
+	}
+}