Minor cleanup for readability

app/main.go

 func handleCommand(ctx Context, command Command) ExitStatus {
 	// fmt.Printf("handleCommand():command=%#v\n", command)
 	switch command.command_type {
+
 	case CommandTypeNone:
 		return 0
+
 	case CommandTypeBuiltinExit:
 		os.Exit(0)
+
 	case CommandTypeBuiltinEcho:
 		fmt.Fprintln(ctx.stdout, strings.Join(command.tokens[1:], " "))
+		return 0
+
 	case CommandTypeBuiltinPwd:
 		if len(command.tokens) != 1 {
 			fmt.Fprintln(ctx.stderr, "usage: pwd")
 			panic("error getting current working directory")
 		}
 		fmt.Fprintln(ctx.stdout, cwd_path)
+		return 0
+
 	case CommandTypeBuiltinType:
 		if len(command.tokens) != 2 {
 			fmt.Fprintln(ctx.stderr, "usage: type COMMAND")
 		default:
 			fmt.Fprintf(ctx.stdout, "%s is a shell builtin\n", parsed.tokens[0])
 		}
+		return 0
+
 	case CommandTypeExternal:
 		cmd := exec.Command(command.exec_path, command.tokens[1:]...)
 		cmd.Args = command.tokens
 				return ExitStatus(65535)
 			}
 		}
-		return ExitStatus(0)
+		return 0
+
 	default:
 		panic("unknown command type")
 	}