SectionedDataSource.getItem can return null

app/src/main/java/org/tasks/tasklist/DiffCallback.kt

@@ -18,7 +18,7 @@ internal class DiffCallback(private val old: SectionedDataSource, private val ne
         return if (isHeader) {
             old.sortMode == new.sortMode && old.getHeaderValue(oldPosition) == new.getHeaderValue(newPosition)
         } else {
-            old.getItem(oldPosition).id == new.getItem(newPosition).id
+            old.getItem(oldPosition)!!.id == new.getItem(newPosition)!!.id
         }
     }
 
@@ -26,8 +26,8 @@ internal class DiffCallback(private val old: SectionedDataSource, private val ne
         if (new.isHeader(newPosition)) {
             return old.getSection(oldPosition).collapsed == new.getSection(newPosition).collapsed
         }
-        val oldItem = old.getItem(oldPosition)
+        val oldItem = old.getItem(oldPosition)!!
-        val newItem = new.getItem(newPosition)
+        val newItem = new.getItem(newPosition)!!
         return oldItem == newItem && oldItem.getIndent() == adapter.getIndent(newItem)
     }
 }

app/src/main/java/org/tasks/tasklist/SectionedDataSource.kt

@@ -6,8 +6,12 @@ import org.tasks.data.TaskContainer
 import org.tasks.date.DateTimeUtils
 import java.util.*
 
-class SectionedDataSource constructor(tasks: List<TaskContainer>, disableHeaders: Boolean, val sortMode: Int, private val collapsed: MutableSet<Long>) {
+class SectionedDataSource constructor(
-
+        tasks: List<TaskContainer>,
+        disableHeaders: Boolean,
+        val sortMode: Int,
+        private val collapsed: MutableSet<Long>
+) {
     private val tasks = tasks.toMutableList()
 
     private val sections = if (disableHeaders) {
@@ -16,9 +20,9 @@ class SectionedDataSource constructor(tasks: List<TaskContainer>, disableHeaders
         getSections()
     }
 
-    fun getItem(position: Int): TaskContainer = tasks[sectionedPositionToPosition(position)]
+    fun getItem(position: Int): TaskContainer? = tasks.getOrNull(sectionedPositionToPosition(position))
 
-    fun getHeaderValue(position: Int): Long = sections[position]!!.value
+    fun getHeaderValue(position: Int): Long = getSection(position).value
 
     fun isHeader(position: Int) = sections[position] != null
 

app/src/main/java/org/tasks/widget/ScrollableViewsFactory.kt

@@ -89,10 +89,7 @@ internal class ScrollableViewsFactory(
         return 1
     }
 
-    override fun getItemId(position: Int): Long {
+    override fun getItemId(position: Int) = getTask(position)?.id ?: 0
-        val task = getTask(position)
-        return task?.id ?: 0
-    }
 
     override fun hasStableIds(): Boolean {
         return true
@@ -208,9 +205,7 @@ internal class ScrollableViewsFactory(
         return null
     }
 
-    private fun getTask(position: Int): TaskContainer? {
+    private fun getTask(position: Int): TaskContainer? = tasks.getItem(position)
-        return if (position < tasks.size) tasks[position] else null
-    }
 
     private suspend fun getQuery(filter: Filter?, subtasks: SubtaskInfo): List<String> {
         val queries = getQuery(preferences, filter!!, subtasks)