Fix drag and drop differ

app/src/main/java/org/tasks/activities/DragAndDropDiffer.kt

@@ -48,15 +48,18 @@ interface DragAndDropDiffer<T, R> : ListUpdateCallback {
     @ExperimentalCoroutinesApi
     fun initializeDiffer(list: List<T>): R {
         val initial = transform(list)
-        scope.launch(Dispatchers.Main) {
         flow
             .scan(Pair(initial, null), { last: Pair<R, DiffUtil.DiffResult?>, next: R ->
                 calculateDiff(last, next)
             })
             .drop(1)
             .flowOn(Executors.newSingleThreadExecutor().asCoroutineDispatcher())
-                .collect { applyDiff(it) }
+            .onEach {
+                withContext(Dispatchers.Main) {
+                    applyDiff(it)
                 }
+            }
+            .launchIn(scope)
         return initial
     }