refactor: centralise app name validation

cli/app/logs.go

@@ -2,7 +2,6 @@ package app
 
 import (
 	"context"
-	"errors"
 	"fmt"
 	"io"
 	"os"
@@ -64,10 +63,7 @@ var appLogsCommand = &cli.Command{
 	ArgsUsage: "[<service>]",
 	Usage:     "Tail app logs",
 	Action: func(c *cli.Context) error {
-		appName := c.Args().First()
-		if appName == "" {
-			internal.ShowSubcommandHelpAndError(c, errors.New("no app name provided"))
-		}
+		appName := internal.ValidateAppNameArg(c)
 
 		appFiles, err := config.LoadAppFiles("")
 		if err != nil {