replace exitOnError with a deferred exit function.

this ensures the closer() cleanup function is always called.

cmd/vbantxt/main.go

@@ -47,12 +47,28 @@ func (f *Flags) String() string {
 	)
 }
 
-func exitOnError(err error) {
-	fmt.Fprintf(os.Stderr, "Error: %s\n", err)
-	os.Exit(1)
+func main() {
+	var exitCode int
+
+	// Defer exit with the final exit code
+	defer func() {
+		if exitCode != 0 {
+			os.Exit(exitCode)
+		}
+	}()
+
+	closer, err := run()
+	if closer != nil {
+		defer closer()
+	}
+	if err != nil {
+		log.Error(err)
+		exitCode = 1
+	}
 }
 
-func main() {
+// run contains the main application logic and returns a closer function and any error.
+func run() (func(), error) {
 	var flags Flags
 
 	// VBAN specific flags
@@ -66,7 +82,7 @@ func main() {
 
 	configDir, err := os.UserConfigDir()
 	if err != nil {
-		exitOnError(fmt.Errorf("failed to get user config directory: %w", err))
+		return nil, fmt.Errorf("failed to get user config directory: %w", err)
 	}
 	defaultConfigPath := filepath.Join(configDir, "vbantxt", "config.toml")
 
@@ -98,7 +114,7 @@ func main() {
 		fmt.Fprintf(os.Stderr, "%s\n", ffhelp.Flags(fs, "vbantxt [flags] <vban commands>"))
 		os.Exit(0)
 	case err != nil:
-		exitOnError(fmt.Errorf("failed to parse flags: %w", err))
+		return nil, fmt.Errorf("failed to parse flags: %w", err)
 	}
 
 	if flags.Version {
@@ -108,7 +124,7 @@ func main() {
 
 	level, err := log.ParseLevel(flags.Loglevel)
 	if err != nil {
-		exitOnError(fmt.Errorf("invalid log level: %s", flags.Loglevel))
+		return nil, fmt.Errorf("invalid log level %q", flags.Loglevel)
 	}
 	log.SetLevel(level)
 
@@ -116,16 +132,18 @@ func main() {
 
 	client, closer, err := createClient(&flags)
 	if err != nil {
-		exitOnError(err)
+		return nil, fmt.Errorf("failed to create VBAN client: %w", err)
 	}
-	defer closer()
 
 	commands := fs.GetArgs()
 	if len(commands) == 0 {
-		exitOnError(errors.New("no VBAN commands provided"))
+		return closer, errors.New(
+			"no VBAN commands provided; please provide at least one command as an argument",
+		)
 	}
 
 	sendCommands(client, commands)
+	return closer, nil
 }
 
 // versionFromBuild retrieves the version information from the build metadata.
@@ -133,7 +151,7 @@ func versionFromBuild() string {
 	if version == "" {
 		info, ok := debug.ReadBuildInfo()
 		if !ok {
-			exitOnError(errors.New("failed to read build info"))
+			return "(unable to read build info)"
 		}
 		version = strings.Split(info.Main.Version, "-")[0]
 	}