Function duckdb_appender_close

pub unsafe extern "C" fn duckdb_appender_close(
    appender: duckdb_appender,
) -> duckdb_state

Closes the appender by flushing all intermediate states and closing it for further appends. If flushing the data triggers a constraint violation or any other error, then all data is invalidated, and this function returns DuckDBError. Call duckdb_appender_error to obtain the error message followed by duckdb_appender_destroy to destroy the invalidated appender.

@param appender The appender to flush and close. @return DuckDBSuccess on success or DuckDBError on failure.