message: Fix housekeeping on Table::m_index_accessors
diff: @@ -733,9 +733,10 @@ void Table::do_erase_root_column(ColKey col_key)
  ref_type index_ref = m_index_refs.get_as_ref(col_ndx);
  if (index_ref) {
  Array::destroy_deep(index_ref, m_index_refs.get_alloc());
  - }
  - delete m_index_accessors[col_ndx];
  m_index_refs.set(col_ndx, 0);
  + delete m_index_accessors[col_ndx];
  + m_index_accessors[col_ndx] = nullptr;
  + }
  m_opposite_table.set(col_ndx, 0);
  m_opposite_column.set(col_ndx, 0);
  m_index_accessors[col_ndx] = nullptr;
  @@ -745,6 +746,10 @@ void Table::do_erase_root_column(ColKey col_key)
  m_top.adjust(top_position_for_column_key, 2);
  build_column_mapping();
  + while (m_index_accessors.size() > m_leaf_ndx2colkey.size()) {
  + REALM_ASSERT(m_index_accessors.back() == nullptr);
  + m_index_accessors.erase(m_index_accessors.end() - 1);
  + }
  }
  LinkType Table::get_link_type(ColKey col_key) const
  