Use notifyDataSetChanged for potentially structural modification.

This has the potential to change the structure of the result set
displayed in the recycler view. Thus the functions that tell it the
structure changed need to be called. For an immediate fix, changing
this back to notifyDataSetChanged seems to resolve the crash.

app/src/main/java/org/thoughtcrime/securesms/conversationlist/ConversationListSearchAdapter.java

@@ -107,7 +107,7 @@ class ConversationListSearchAdapter extends    RecyclerView.Adapter<Conversation
 
   void updateResults(@NonNull SearchResult result) {
     this.searchResult = result;
-    notifyItemRangeChanged(0, getItemCount());
+    notifyDataSetChanged();
   }
 
   @Nullable