Need help converting Oracle trigger to Mariadb - oracle

Question

I am new to mariadb trigger. I had this trigger in Oracle. Need help to convert it to mariadb:
DECLARE
v_newVal NUMBER(12) := 0;
v_incval NUMBER(12) := 0;
BEGIN
IF INSERTING AND :new.id IS NULL THEN
SELECT hvr_storyboards_id_SEQ.NEXTVAL INTO v_newVal FROM DUAL;
-- If this is the first time this table have been inserted into (sequence == 1)
IF v_newVal = 1 THEN
--get the max indentity value from the table
SELECT NVL(max(id),0) INTO v_newVal FROM hvr_storyboards;
v_newVal := v_newVal + 1;
--set the sequence to that value
LOOP
EXIT WHEN v_incval>=v_newVal;
SELECT hvr_storyboards_id_SEQ.nextval INTO v_incval FROM dual;
END LOOP;
END IF;
--used to emulate LAST_INSERT_ID()
--mysql_utilities.identity := v_newVal;
-- assign the value from the sequence to emulate the identity column
--:new.id := v_newVal;
END IF;
END;
I use a online conversion tool then manage to create it as
DECLARE
v_newVal NUMBER(12) := 0;
v_incval NUMBER(12) := 0;
BEGIN
IF INSERTING AND :new.id IS NULL THEN
SELECT hvr_storyboards_id_SEQ.NEXTVAL INTO v_newVal FROM DUAL;
-- If this is the first time this table have been inserted into (sequence == 1)
IF v_newVal = 1 THEN
--get the max indentity value from the table
SELECT NVL(max(id),0) INTO v_newVal FROM hvr_storyboards;
v_newVal := v_newVal + 1;
--set the sequence to that value
LOOP
EXIT WHEN v_incval>=v_newVal;
SELECT hvr_storyboards_id_SEQ.nextval INTO v_incval FROM dual;
END LOOP;
END IF;
--used to emulate LAST_INSERT_ID()
--mysql_utilities.identity := v_newVal;
-- assign the value from the sequence to emulate the identity column
--:new.id := v_newVal;
END IF;
END;
but I am getting this error
An exception occurred while executing 'INSERT INTO hvr_storyboards (name, updated_datetime, domain_id, ticker_id, updated_by) VALUES (?, ?, ?, ?, ?)' with params ["this is a test 6 - Ace", null, 21, null, null]: SQLSTATE[42S22]: Column not found: 1054 Unknown column 'INSERTING' in 'field list'
what did I do wrong?