Major Description
ARRAY_APPEND and ARRAY_REMOVE should create the array value when it's null
Test case:
create table test_array (
ID VARCHAR NOT NULL,
MYARRAY VARCHAR ARRAY
CONSTRAINT testpk PRIMARY KEY (ID)
);
upsert into test_array (id) values ('test');
upsert into test_array select id,array_append(myarray,'testValue') from test_array;
select ID,ARRAY_TO_STRING(MYARRAY, ',') from test_array;
