Expression is of wrong type when sending nested array to Function - plsql

Question

I want to send a collection to a Function, but I keep getting an error.
I defined the RECORD and TYPES in my Package Header and Implemented the body aswell. I dont understand why I cant send a simple collection as a parameter, the idea is for me to loop through the collection and do some comparisation then return a char within a sql statement.
Been struggling with this for a week now, any help is appreciated.
Exact error:
ORA-06550: line 9, column 45:
PLS-00382: expression is of wrong type
ORA-06550: line 9, column 40:
PLS-00306: wrong number or types of arguments in call to 'TEST_F'
ORA-06550: line 9, column 23:
PL/SQL: ORA-00904: "PACKAGE_SS"."TEST_F": invalid identifier
ORA-06550: line 9, column 3:
PL/SQL: SQL Statement ignored
Header:
create or replace
PACKAGE PACKAGE_SS AS
type t_itemnumber is table of varchar2(100) index by BINARY_INTEGER;
type t_alternative_rec is record
(
itemnumber t_itemnumber
);
type t_alternative_prev is table of t_alternative_rec INDEX BY BINARY_INTEGER;
type t_procestype_rec is record
(
procestype char
);
TYPE result_table IS TABLE OF t_procestype_rec;
FUNCTION test_f(p_items_prev IN t_alternative_prev) RETURN result_table PIPELINED;
END AOPA_VALIDATE_SS;
The package body looks like this:
create or replace
PACKAGE BODY PACKAGE_SS AS
FUNCTION test_f(p_items_prev IN t_alternative_prev) RETURN result_table PIPELINED IS
processType char(1) := 'U';
rec t_procestype_rec :=null;
BEGIN
DBMS_OUTPUT.PUT_LINE('ENTERD ');
if (processType= 'U') then
select 'U' into rec from dual;
end if;
if (processType='C') then
select 'C' into rec from dual;
end if;
if (processType='D') then
select 'D' into rec from dual;
end if;
pipe row (rec);
return;
END test_f;
END PACKAGE_SS;
Usage plsql script:
DECLARE
prev_rev_alternatives PACKAGE_SS.t_alternative_prev;
BEGIN
prev_rev_alternatives(1).itemnumber(10) := 'PR454545';
prev_rev_alternatives(1).itemnumber(20) := 'PR333333';
SELECT * FROM table(PACKAGE_SS.test_f(prev_rev_alternatives));
END;

Answer 1

There are two things which my eyes fall upon:
Usage of SELECT without INTO in an anonymous PLSQL block is not supposed to work.
Usage of types in an SQL statement requires the type defined as an object, not within a package specification.
Try
CREATE TYPE
https://docs.oracle.com/cd/B19306_01/server.102/b14200/statements_8001.htm
and
SELECT * INTO ... FROM ...
This might help.