Unclear memory de-allocation code in src/libs/zbxdbcache/nextchecks.c

In file src/libs/zbxdbcache/nextchecks.c, function DCflush_nextchecks(), it is not clear why there is only "zbx_free(trigger->expression);", but there is no "zbx_free(trigger->new_error);". Could it be a memory leak ?
For example, In file src/libs/zbxdbcache/dbcache.c, function DCmass_update_triggers(), there are both "zbx_free(trigger->expression);" and "zbx_free(trigger->new_error);".