命名修正など

app/src/main/res/layout/activity_main.xml

@@ -17,7 +17,7 @@
         app:layout_constraintStart_toStartOf="parent"
         app:layout_constraintTop_toTopOf="parent"
         app:navGraph="@navigation/main_nav"
-        tools:layout="@layout/fragment_blank" />
+        tools:layout="@layout/fragment_debug_menu" />
 
     <com.google.android.material.bottomnavigation.BottomNavigationView
         android:id="@+id/bottom_nav"