BT_ASSERT_PRE_NON_NULL(length_field, "Length field");
BT_ASSERT_PRE_FIELD_COMMON_IS_SET((void *) length_field, "Length field");
BT_ASSERT_PRE_NON_NULL(length_field, "Length field");
BT_ASSERT_PRE_FIELD_COMMON_IS_SET((void *) length_field, "Length field");