→ BottomNavigationView 에 Navigation 연결할때 발생
val mainfrg = binding.mainFrag
val navController = mainfrg.findNavController()
binding.mainBottomnav.setupWithNavController(navController)
val navHostFragment =supportFragmentManager.findFragmentById(R.id.main_frag) as NavHostFragment
val navController = navHostFragment.navController
binding.mainBottomnav.setupWithNavController(navController)