Fix IllegalStateException when clicking login after logout

The previous login result was stored as live data and
prevented AuthenticationFragment from being shown
properly. However, an attempt to destroy RecipesFragment
was made. This attempt caused IllegalStateException
when accessing view in onDestroyView.

app/src/main/java/gq/kirmanak/mealient/ui/auth/AuthenticationFragment.kt

@@ -14,6 +14,7 @@ import gq.kirmanak.mealient.data.network.NetworkError
 import gq.kirmanak.mealient.databinding.FragmentAuthenticationBinding
 import gq.kirmanak.mealient.extensions.checkIfInputIsEmpty
 import gq.kirmanak.mealient.extensions.executeOnceOnBackPressed
+import kotlinx.coroutines.launch
 import timber.log.Timber
 
 @AndroidEntryPoint
@@ -33,7 +34,6 @@ class AuthenticationFragment : Fragment(R.layout.fragment_authentication) {
         binding.button.setOnClickListener { onLoginClicked() }
         (requireActivity() as? AppCompatActivity)?.supportActionBar?.title =
             getString(R.string.app_name)
-        viewModel.authenticationResult.observe(viewLifecycleOwner, ::onAuthenticationResult)
     }
 
     private fun onLoginClicked(): Unit = with(binding) {
@@ -48,7 +48,9 @@ class AuthenticationFragment : Fragment(R.layout.fragment_authentication) {
         } ?: return
 
         button.isClickable = false
-        viewModel.authenticate(email, pass)
+        viewLifecycleOwner.lifecycleScope.launch {
+            onAuthenticationResult(viewModel.authenticate(email, pass))
+        }
     }
 
     private fun onAuthenticationResult(result: Result<Unit>) {

app/src/main/java/gq/kirmanak/mealient/ui/auth/AuthenticationViewModel.kt

@@ -1,6 +1,9 @@
 package gq.kirmanak.mealient.ui.auth
 
-import androidx.lifecycle.*
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.asLiveData
+import androidx.lifecycle.viewModelScope
 import dagger.hilt.android.lifecycle.HiltViewModel
 import gq.kirmanak.mealient.data.auth.AuthRepo
 import kotlinx.coroutines.flow.MutableStateFlow
@@ -28,10 +31,6 @@ class AuthenticationViewModel @Inject constructor(
     var authRequested: Boolean by authRequestsFlow::value
     var showLoginButton: Boolean by showLoginButtonFlow::value
 
-    private val _authenticationResult = MutableLiveData<Result<Unit>>()
-    val authenticationResult: LiveData<Result<Unit>>
-        get() = _authenticationResult
-
     init {
         viewModelScope.launch {
             authRequestsFlow.collect { isRequested ->
@@ -41,18 +40,9 @@ class AuthenticationViewModel @Inject constructor(
         }
     }
 
-    fun authenticate(username: String, password: String) {
-        Timber.v("authenticate() called with: username = $username, password = $password")
-        viewModelScope.launch {
-            runCatching {
-                authRepo.authenticate(username, password)
-            }.onFailure {
-                Timber.e(it, "authenticate: can't authenticate")
-                _authenticationResult.value = Result.failure(it)
-            }.onSuccess {
-                Timber.d("authenticate: authenticated")
-                _authenticationResult.value = Result.success(Unit)
-            }
-        }
+    suspend fun authenticate(username: String, password: String): Result<Unit> = runCatching {
+        authRepo.authenticate(username, password)
+    }.onFailure {
+        Timber.e(it, "authenticate: can't authenticate")
     }
 }