Fix crash with moveToLastSeen()

src/org/thoughtcrime/securesms/ConversationActivity.java

@@ -301,9 +301,12 @@ public class ConversationActivity extends PassphraseRequiredActionBarActivity
           @Override
           public void onSuccess(Boolean result) {
             if (result != null && result) {
+              Log.i(TAG, "Finished loading draft");
               Util.runOnMain(() -> {
                 if (fragment != null && fragment.isResumed()) {
                   fragment.moveToLastSeen();
+                } else {
+                  Log.w(TAG, "Wanted to move to the last seen position, but the fragment was in an invalid state");
                 }
               });
             }

src/org/thoughtcrime/securesms/ConversationFragment.java

@@ -191,11 +191,19 @@ public class ConversationFragment extends Fragment
   }
 
   public void moveToLastSeen() {
-    if (lastSeen > 0) {
+    if (lastSeen <= 0) {
+      Log.i(TAG, "No need to move to last seen.");
+      return;
+    }
+
+    if (list == null || getListAdapter() == null) {
+      Log.w(TAG, "Tried to move to last seen position, but we hadn't initialized the view yet.");
+      return;
+    }
+
     int position = getListAdapter().findLastSeenPosition(lastSeen);
     scrollToLastSeenPosition(position);
   }
-  }
 
   private void initializeResources() {
     this.recipient         = Recipient.from(getActivity(), getActivity().getIntent().getParcelableExtra(ConversationActivity.ADDRESS_EXTRA), true);