[Script Error]: stingray::plugin_api::unit::node failed, UnitReference is not valid.Assertion failed unit != nullptr
at D:\agent-work\data-dir\engine_release_season_3_engineer_2020_10_28\runtime\application\plugin\c_api\c_api_unit.cpp:71
in function stingray::plugin_api::unit::node
Who can tell me what this means.