message: Fix crash in FileViewer::ShowReferences()
diff: @@ -324,6 +324,7 @@ void FileViewer::ShowReferences(CatalogPtr catalog, CatalogItemPtr item, int def
  if (m_basePath.empty())
  m_basePath = wxPathOnly(catalog->GetFileName());
  + if (item)
  m_references = item->GetReferences();
  m_file->Clear();
  