_dir before _index_writer lifetime dependency?InvertedIndexCacheHandle over raw handles for paired release/retention?CLucene uses ErrorContext + local FINALLY helpers, not Doris exception flow.
ErrorContext + FINALLY / FINALLY_CLOSE / FINALLY_EXCEPTION, not ad hoc try/catch?_data_bitmap and _null_bitmap?op_not is const in signature but mutates shared state — callers handle this?