fix crash when logging out while on conversations (#2895)

* fix crash when logging out while on conversations

* fix code formatting

app/src/main/java/com/keylesspalace/tusky/components/conversation/ConversationsViewModel.kt

@@ -27,6 +27,7 @@ import com.keylesspalace.tusky.db.AccountManager
 import com.keylesspalace.tusky.db.AppDatabase
 import com.keylesspalace.tusky.network.MastodonApi
 import com.keylesspalace.tusky.usecase.TimelineCases
+import com.keylesspalace.tusky.util.EmptyPagingSource
 import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.rx3.await
@@ -43,7 +44,14 @@ class ConversationsViewModel @Inject constructor(
     val conversationFlow = Pager(
         config = PagingConfig(pageSize = 30),
         remoteMediator = ConversationsRemoteMediator(api, database, accountManager),
-        pagingSourceFactory = { database.conversationDao().conversationsForAccount(accountManager.activeAccount!!.id) }
+        pagingSourceFactory = {
+            val activeAccount = accountManager.activeAccount
+            if (activeAccount == null) {
+                EmptyPagingSource()
+            } else {
+                database.conversationDao().conversationsForAccount(activeAccount.id)
+            }
+        }
     )
         .flow
         .map { pagingData ->

app/src/main/java/com/keylesspalace/tusky/components/timeline/viewmodel/CachedTimelineViewModel.kt

@@ -43,6 +43,7 @@ import com.keylesspalace.tusky.entity.Poll
 import com.keylesspalace.tusky.network.FilterModel
 import com.keylesspalace.tusky.network.MastodonApi
 import com.keylesspalace.tusky.usecase.TimelineCases
+import com.keylesspalace.tusky.util.EmptyPagingSource
 import com.keylesspalace.tusky.viewdata.StatusViewData
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.asExecutor
@@ -85,7 +86,7 @@ class CachedTimelineViewModel @Inject constructor(
         pagingSourceFactory = {
             val activeAccount = accountManager.activeAccount
             if (activeAccount == null) {
-                EmptyTimelinePagingSource()
+                EmptyPagingSource()
             } else {
                 db.timelineDao().getStatuses(activeAccount.id)
             }.also { newPagingSource ->

app/src/main/java/com/keylesspalace/tusky/components/timeline/viewmodel/EmptyTimelinePagingSource.kt

@@ -1,11 +0,0 @@
-package com.keylesspalace.tusky.components.timeline.viewmodel
-
-import androidx.paging.PagingSource
-import androidx.paging.PagingState
-import com.keylesspalace.tusky.db.TimelineStatusWithAccount
-
-class EmptyTimelinePagingSource : PagingSource<Int, TimelineStatusWithAccount>() {
-    override fun getRefreshKey(state: PagingState<Int, TimelineStatusWithAccount>): Int? = null
-
-    override suspend fun load(params: LoadParams<Int>): LoadResult<Int, TimelineStatusWithAccount> = LoadResult.Page(emptyList(), null, null)
-}

app/src/main/java/com/keylesspalace/tusky/util/EmptyPagingSource.kt

@@ -0,0 +1,10 @@
+package com.keylesspalace.tusky.util
+
+import androidx.paging.PagingSource
+import androidx.paging.PagingState
+
+class EmptyPagingSource<T : Any> : PagingSource<Int, T>() {
+    override fun getRefreshKey(state: PagingState<Int, T>): Int? = null
+
+    override suspend fun load(params: LoadParams<Int>): LoadResult<Int, T> = LoadResult.Page(emptyList(), null, null)
+}