Use errors.AsType for error unwrapping

Author: kindermax

docs/docs/changelog.md

@@ -3,6 +3,10 @@ id: changelog
 title: Changelog
 ---
 
+## [Unreleased](https://github.com/lets-cli/lets/releases/tag/v0.0.X)
+
+* `[Refactoring]` Use Go 1.26 `errors.AsType` for type-safe error unwrapping.
+
 ## [0.0.61](https://github.com/lets-cli/lets/releases/tag/v0.0.61)
 
 * `[Changed]` Install script now installs to `$HOME/.lets/bin`, exposes `lets` through a user PATH symlink, and stops on old non-Homebrew `/usr/local/bin/lets` installs. Issue [#121](https://github.com/lets-cli/lets/issues/121)

internal/cli/cli.go

@@ -127,8 +127,7 @@ func Main(version string, buildDate string) int {
 	defer cancelUpdateCheck()
 
 	if err := rootCmd.ExecuteContext(ctx); err != nil {
-		var depErr *executor.DependencyError
-		if errors.As(err, &depErr) {
+		if depErr, ok := errors.AsType[*executor.DependencyError](err); ok {
 			log.Errorf("%s", depErr.TreeMessage())
 			log.Errorf("%s", depErr.FailureMessage())
 
@@ -167,9 +166,13 @@ func getContext() context.Context {
 }
 
 func getExitCode(err error, defaultCode int) int {
-	var exitCoder interface{ ExitCode() int }
-	if errors.As(err, &exitCoder) {
-		return exitCoder.ExitCode()
+	type errorWithExitCode interface {
+		error
+		ExitCode() int
+	}
+
+	if errWithExitCode, ok := errors.AsType[errorWithExitCode](err); ok {
+		return errWithExitCode.ExitCode()
 	}
 
 	return defaultCode

internal/cmd/root_test.go

@@ -12,6 +12,22 @@ import (
 	"github.com/spf13/cobra"
 )
 
+type testErrorWithExitCode interface {
+	error
+	ExitCode() int
+}
+
+func requireErrorWithExitCode(t *testing.T, err error) testErrorWithExitCode {
+	t.Helper()
+
+	errWithExitCode, ok := errors.AsType[testErrorWithExitCode](err)
+	if !ok {
+		t.Fatal("expected error with exit code")
+	}
+
+	return errWithExitCode
+}
+
 func newTestRootCmd(args []string) (rootCmd *cobra.Command) {
 	root := CreateRootCommand("v0.0.0-test", "")
 	root.SetArgs(args)
@@ -91,12 +107,9 @@ func TestRootCmdWithConfig(t *testing.T) {
 			t.Fatal("expected unknown command error")
 		}
 
-		var exitCoder interface{ ExitCode() int }
-		if !errors.As(err, &exitCoder) {
-			t.Fatal("expected error with exit code")
-		}
+		errWithExitCode := requireErrorWithExitCode(t, err)
 
-		if exitCode := exitCoder.ExitCode(); exitCode != 2 {
+		if exitCode := errWithExitCode.ExitCode(); exitCode != 2 {
 			t.Fatalf("expected exit code 2, got %d", exitCode)
 		}
 
@@ -121,12 +134,9 @@ func TestRootCmdWithConfig(t *testing.T) {
 			t.Fatal("expected unknown command error")
 		}
 
-		var exitCoder interface{ ExitCode() int }
-		if !errors.As(err, &exitCoder) {
-			t.Fatal("expected error with exit code")
-		}
+		errWithExitCode := requireErrorWithExitCode(t, err)
 
-		if exitCode := exitCoder.ExitCode(); exitCode != 2 {
+		if exitCode := errWithExitCode.ExitCode(); exitCode != 2 {
 			t.Fatalf("expected exit code 2, got %d", exitCode)
 		}
 
@@ -247,12 +257,9 @@ func TestSelfCmd(t *testing.T) {
 			t.Fatal("expected unknown command error")
 		}
 
-		var exitCoder interface{ ExitCode() int }
-		if !errors.As(err, &exitCoder) {
-			t.Fatal("expected error with exit code")
-		}
+		errWithExitCode := requireErrorWithExitCode(t, err)
 
-		if exitCode := exitCoder.ExitCode(); exitCode != 2 {
+		if exitCode := errWithExitCode.ExitCode(); exitCode != 2 {
 			t.Fatalf("expected exit code 2, got %d", exitCode)
 		}
 
@@ -283,12 +290,9 @@ func TestSelfCmd(t *testing.T) {
 			t.Fatal("expected unknown command error")
 		}
 
-		var exitCoder interface{ ExitCode() int }
-		if !errors.As(err, &exitCoder) {
-			t.Fatal("expected error with exit code")
-		}
+		errWithExitCode := requireErrorWithExitCode(t, err)
 
-		if exitCode := exitCoder.ExitCode(); exitCode != 2 {
+		if exitCode := errWithExitCode.ExitCode(); exitCode != 2 {
 			t.Fatalf("expected exit code 2, got %d", exitCode)
 		}
 

internal/executor/dependency_error.go

@@ -25,17 +25,15 @@ func (e *DependencyError) Unwrap() error { return e.Err }
 
 // ExitCode propagates the exit code from the innermost ExecuteError, or returns 1.
 func (e *DependencyError) ExitCode() int {
-	var exitErr *ExecuteError
-	if errors.As(e.Err, &exitErr) {
+	if exitErr, ok := errors.AsType[*ExecuteError](e.Err); ok {
 		return exitErr.ExitCode()
 	}
 
 	return 1
 }
 
 func (e *DependencyError) FailureMessage() string {
-	var executeErr *ExecuteError
-	if errors.As(e.Err, &executeErr) {
+	if executeErr, ok := errors.AsType[*ExecuteError](e.Err); ok {
 		return executeErr.Cause().Error()
 	}
 
@@ -67,8 +65,7 @@ func (e *DependencyError) TreeMessage() string {
 // prependToChain prepends name to the chain in err if err is already a *DependencyError,
 // otherwise wraps err in a new single-element DependencyError.
 func prependToChain(name string, err error) error {
-	var depErr *DependencyError
-	if errors.As(err, &depErr) {
+	if depErr, ok := errors.AsType[*DependencyError](err); ok {
 		return &DependencyError{Chain: append([]string{name}, depErr.Chain...), Err: depErr.Err}
 	}
 

internal/executor/executor.go

@@ -39,8 +39,7 @@ func (e *ExecuteError) Cause() error {
 
 // ExitCode will return exit code from underlying ExitError or returns default error code.
 func (e *ExecuteError) ExitCode() int {
-	var exitErr *exec.ExitError
-	if ok := errors.As(e.err, &exitErr); ok {
+	if exitErr, ok := errors.AsType[*exec.ExitError](e.err); ok {
 		return exitErr.ExitCode()
 	}