Error: ORA-00604: error produced at level 1 of recursivo - SQL ORA-01400: an insertion NULL cannot be made in ("SYS"."obj$"."name")

I have this pl/sql function:
------------------
CREATE OR REPLACE
FUNCTION GET_ISSUER (CpyCode VARCHAR2, ItemId VARCHAR2, TitleType VARCHAR2, InvEntity VARCHAR2)
 RETURN VARCHAR2
IS

 type issuer_type is ref cursor;
 c_issuer  issuer_type;
 
 v_issuer  ISSUER_CFG%ROWTYPE;
 type issuer_rec is record
   (num_errors ISSUER_CFG.ACEPTED%TYPE,
    issuer_id  ISSUER_CFG.ISSUER_ID%TYPE);
 type v_issuers is table of issuer_rec
   index by binary_integer;  
 v_iss v_issuers;
 
 i binary_integer := 0;

 aux1 varchar2(12);
 aux2 number(1);
 sSQL varchar2(2000);
 
BEGIN
 
   sSQL :=
      'SELECT CPY_CODE, ISSUER_ID, TITLE_TYPE, INV_ENTITY, NAME, ACEPTED ' ||
      'FROM ISSUER_CFG ' ||
      'WHERE ' ||
      ' CPY_CODE = "' || CpyCode || '" AND TITLE_TYPE = "' || TitleType || '"';
         
   IF InvEntity != null AND trim(InvEntity) != "" THEN
      sSQL := sSQL || ' AND INV_ENTITY = "' || InvEntity || '"';
   END IF;

   OPEN c_issuer FOR sSQL;
       
   -- get cursor      
   LOOP    
     FETCH cur_issuer INTO v_issuer;
     EXIT WHEN cur_issuer%NOTFOUND;
     i := i + 1;
     v_iss(i).issuer_id  := v_issuer.ISSUER_ID;       
     -- get errors number
     v_iss(i).num_errors := GET_COINCIDENCES(ItemId, v_iss(i).issuer_id);          
   END LOOP;    

   -- order issuers by less number errors      
   FOR j IN 1 .. v_iss.COUNT-1 LOOP    
     IF  v_iss(j).num_errors >  v_iss(j+1).num_errors THEN
        aux1 := v_iss(j).num_errors;
        aux2 := v_iss(j).issuer_id;

        v_iss(j).num_errors := v_iss(j+1).num_errors;
        v_iss(j).issuer_id  := v_iss(j+1).issuer_id;

        v_iss(j+1).num_errors := aux1;
        v_iss(j+1).issuer_id  := aux2;
     END IF;          
   END LOOP;

   IF v_iss.COUNT = 0  OR v_iss(1).num_errors = length(ItemId) THEN
      RETURN '0';
   ELSE  
      RETURN v_iss(1).issuer_id;
   END IF;  
END;

------------------

When I compile it gives me this error:

Error: ORA-00604: error produced at level 1 of recursive SQL
ORA-01400: an insertion NULL cannot be made in ("SYS"."obj$"."name")


What can I do?
Help me plase