Fix Post->PreRun, add more comments

cmd/av/main.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"fmt"
 	"github.com/aviator-co/av/internal/config"
 	"github.com/sirupsen/logrus"
 	"github.com/spf13/cobra"
@@ -12,14 +13,24 @@ var rootFlags struct {
 }
 
 var rootCmd = &cobra.Command{
-	Use:           "av",
+	Use: "av",
+
+	// Don't automatically print errors or usage information (we handle that ourselves).
+	// Cobra still prints usage if you return cmd.Usage() from RunE.
 	SilenceErrors: true,
 	SilenceUsage:  true,
-	PersistentPostRunE: func(cmd *cobra.Command, args []string) error {
+
+	// Don't show "completion" command in help menu
+	CompletionOptions: cobra.CompletionOptions{
+		HiddenDefaultCmd: true,
+	},
+
+	// Run setup before invoking any child commands.
+	PersistentPreRunE: func(cmd *cobra.Command, args []string) error {
 		if rootFlags.Debug {
 			logrus.SetLevel(logrus.DebugLevel)
+			logrus.WithField("av_version", config.Version).Debug("enabled debug logging")
 		}
-		logrus.Debugf("av version: %s", config.Version)
 		return nil
 	},
 }
@@ -33,6 +44,15 @@ func init() {
 
 func main() {
 	if err := rootCmd.Execute(); err != nil {
+		format := "error: %s\n"
+
+		// In debug mode, show more detailed information about the error
+		// (including the stack trace if using pkg/errors).
+		if rootFlags.Debug {
+			format = "error: %#+v\n"
+		}
+
+		_, _ = fmt.Fprintf(os.Stderr, format, err)
 		os.Exit(1)
 	}
 }

cmd/av/version.go

@@ -9,7 +9,8 @@ import (
 var versionCmd = &cobra.Command{
 	Use:   "version",
 	Short: "print the version information",
-	Run: func(cmd *cobra.Command, args []string) {
+	RunE: func(cmd *cobra.Command, args []string) error {
 		fmt.Println(config.Version)
+		return nil
 	},
 }