mysql - create procedure for IF NOT EXIST

Question

What I'm trying to do

So I'd like to get the id of the item. If it does not exist, then insert it and return it using LAST_INSERT_ID(). So regardless of whether it exists or doesn't, I will have an id at the end.

Found an answer here, even though it's for sql-server: stackoverflow.com/a/8030455/6554121

Here's what I've tried by creating a procedure as follows:

CREATE PROCEDURE `find_map_items` (OUT o INT, IN b TEXT, IN n TEXT, IN q TEXT, IN m TEXT, IN t TEXT)
BEGIN
    IF NOT EXISTS(
        SELECT id 
        FROM item 
        WHERE 
            brand = b 
            AND 
            name = n 
            AND 
            quantity = q 
            AND 
            measurement = m 
            AND 
            type = t
    )
    BEGIN
      INSERT INTO item (brand, name, quantity, measurement, type)
      VALUES (b, n, q, m ,t);
      SELECT LAST_INSERT_ID() INTO o
    END
    ELSE
    BEGIN
        SELECT id 
        FROM item 
        WHERE 
            brand = b 
            AND 
            name = n 
            AND 
            quantity = q 
            AND 
            measurement = m 
            AND 
            type = t
    END
END

But it's giving me some red text and I'm not sure what the problem is:

I'm using MySQL Workbench.