message: ObjLink::operator bool() also includes the ObjKey
diff: @@ -266,11 +266,12 @@ public:
  }
  explicit operator bool() const
  {
  - return m_table_key.operator bool();
  + return bool(m_table_key) && bool(m_obj_key);
  }
  bool is_null() const
  {
  - return !m_table_key.operator bool();
  + return !bool(*this);
  + }
  }
  bool operator==(const ObjLink& other) const
  {
  