Fixed: Hotspot list of books appearing empty(when reopening the ZimHostScreen).

* The issue occurred when reopening the `ZimHostScreen`. The presenter was detaching the view of the previous `ZimHostScreen`, but since the presenter is a singleton, it also cleared the reference to the view attached to the new `ZimHostScreen`. As a result, the `ZimHostPresenter` could not post books because the view reference was null.
* Updated `BasePresenter` so that it only detaches the view if it matches the one currently attached, preventing accidental clearing of the new screen’s view.

app/src/main/java/org/kiwix/kiwixmobile/webserver/ZimHostFragment.kt

@@ -404,7 +404,7 @@ class ZimHostFragment : BaseFragment(), ZimHostCallbacks, ZimHostContract.View {
   override fun onDestroyView() {
     super.onDestroyView()
     unRegisterHotspotService()
-    presenter.detachView()
+    presenter.detachView(this)
   }
 
   private fun unRegisterHotspotService() {

app/src/main/java/org/kiwix/kiwixmobile/webserver/ZimHostPresenter.kt

@@ -30,11 +30,9 @@ import javax.inject.Inject
 @ActivityScope
 class ZimHostPresenter @Inject internal constructor(
   private val dataSource: DataSource
-) : BasePresenter<View>(),
-  Presenter {
-  @Suppress("TooGenericExceptionCaught")
+) : BasePresenter<View>(), Presenter {
   override suspend fun loadBooks(previouslyHostedBooks: Set<String>) {
-    try {
+    runCatching {
       val books = dataSource.getLanguageCategorizedBooks().first()
       books.forEach { item ->
         if (item is BooksOnDiskListItem.BookOnDisk) {
@@ -43,8 +41,8 @@ class ZimHostPresenter @Inject internal constructor(
         }
       }
       view?.addBooks(books)
-    } catch (e: Exception) {
-      Log.e(TAG, "Unable to load books", e)
+    }.onFailure {
+      Log.e(TAG, "Unable to load books", it)
     }
   }
 

core/src/main/java/org/kiwix/kiwixmobile/core/base/BaseContract.kt

@@ -34,7 +34,9 @@ class BaseContract {
 
     /**
      * Drops the reference to the view when destroyed
+     *
+     * @param view the view instance to be detached
      */
-    fun detachView()
+    fun detachView(view: T)
   }
 }

core/src/main/java/org/kiwix/kiwixmobile/core/base/BasePresenter.kt

@@ -32,7 +32,11 @@ abstract class BasePresenter<T : View<*>?> : Presenter<T> {
     this.view = view
   }
 
-  override fun detachView() {
-    view = null
+  override fun detachView(view: T) {
+    // Detach the view only if it matches the one currently attached.
+    // Bug Fix #4409
+    if (this.view == view) {
+      this.view = null
+    }
   }
 }