UGENE crashes on deleting document during sequence exporting

1. Open "human_T1.fa"
2. Use context menu on the document {Export/Import->Export sequences}

   Expected state: "Export selected sequences" dialog appeared

3. Press "Export to file" browse button
4. Delete "human_T1.fa" document in the appeared dialog
   Expected state: the dialog about documents modifications appears.
5. Click "No".
6. Select any file as ouput
7. Export sequences
   Current state: UGENE crashes

Crash report: http://ugene.net/ugenecrashes?id=6732