fix(Android, Stack v5): update stack model after native pop (#3599)

## Description

Currently when doing native pop, the `stackModel` stored in
`StackContainer`
is never updated, therefore leading to an incorrect state held (natively
dismissed fragments are never removed from the state).

This PR changes that.

## Changes

Currently I remove them from the state in `onFragmentDestroyView`,
and it seems to work, however I'm not sure, this is the perfect
place timing-wise. This callback is called only after fragment's
view is destroyed, which might be pretty late in component
lifecycle, and we might execute container operations still taking
into consideration possibly removed screens. We need to look into
that later.

## Before & after - visual documentation

N/A

## Test plan

Only sensible way to test this is to add logging in `StackContainer`
and dismiss few screens natively, and see that the state is updated
(with this fix).

## Checklist

- [x] Ensured that CI passes

Author: kkafar

android/src/main/java/com/swmansion/rnscreens/gamma/stack/host/StackContainer.kt

@@ -2,6 +2,7 @@ package com.swmansion.rnscreens.gamma.stack.host
 
 import android.annotation.SuppressLint
 import android.content.Context
+import android.util.Log
 import androidx.coordinatorlayout.widget.CoordinatorLayout
 import androidx.fragment.app.FragmentManager
 import com.swmansion.rnscreens.gamma.helpers.FragmentManagerHelper
@@ -19,7 +20,14 @@ internal class StackContainer(
 ) : CoordinatorLayout(context) {
     private var fragmentManager: FragmentManager? = null
 
-    private val stackScreenFragments: MutableList<StackScreenFragment> = arrayListOf()
+    /**
+     * Describes most up-to-date view of the stack. It might be different from
+     * state kept by FragmentManager as this data structure is updated immediately,
+     * while operations on fragment manager are scheduled.
+     *
+     * FIXME: In case of native-pop, this might be out of date!
+     */
+    private val stackModel: MutableList<StackScreenFragment> = arrayListOf()
 
     private val pendingPopOperations: MutableList<PopOperation> = arrayListOf()
     private val pendingPushOperations: MutableList<PushOperation> = arrayListOf()
@@ -67,6 +75,8 @@ internal class StackContainer(
     }
 
     private fun performOperations(fragmentManager: FragmentManager) {
+        // TODO: Handle case when we have pop & push of the same screen in single batch.
+
         pendingPopOperations.forEach { performPopOperation(fragmentManager, it) }
         pendingPushOperations.forEach { performPushOperation(fragmentManager, it) }
 
@@ -81,7 +91,7 @@ internal class StackContainer(
         val transaction = fragmentManager.createTransactionWithReordering()
 
         val associatedFragment = StackScreenFragment(WeakReference(this), operation.screen)
-        stackScreenFragments.add(associatedFragment)
+        stackModel.add(associatedFragment)
 
         transaction.add(this.id, associatedFragment)
 
@@ -97,7 +107,7 @@ internal class StackContainer(
         fragmentManager: FragmentManager,
         operation: PopOperation,
     ) {
-        val associatedFragment = stackScreenFragments.find { it.stackScreen === operation.screen }
+        val associatedFragment = stackModel.find { it.stackScreen === operation.screen }
         require(associatedFragment != null) {
             "[RNScreens] Unable to find a fragment to pop."
         }
@@ -115,10 +125,13 @@ internal class StackContainer(
             transaction.commitNowAllowingStateLoss()
         }
 
-        stackScreenFragments.remove(associatedFragment)
+        stackModel.remove(associatedFragment)
     }
 
     internal fun onFragmentDestroyView(fragment: StackScreenFragment) {
+        if (stackModel.remove(fragment) && !fragment.stackScreen.isNativelyDismissed) {
+            Log.e(TAG, "[RNScreens] StackContainer natively popped a screen that was not in model!")
+        }
         delegate.get()?.onScreenDismiss(fragment.stackScreen)
     }