Oracle Cursor - Exception handling within a loop

I have a procedure that I have written that works. Unfortunately some of the data that it returns is 'Null' and hence the corresponding update fails. I want to write exception handling that will output the offending line and continue procesing the next set of data, but I am having problems doing that.

declare
      cursor prodid_cursor is
      
      Select distinct product_id from product_relation where (relation_type = 5 or relation_type = 6 );

      cursor_row prodid_cursor%rowtype;
begin
      for cursor_row  in prodid_cursor
      loop
      Update Product_relation set reserved2 =
                  (select regioncode from group_product_att gp where gp.product_id = cursor_row.product_id and regioncode is not null) where  cursor_row.product_id = Product_relation.product_id;

      end loop;
      commit;
end;


This works till the bad update is encountered and then errors out.  So i tweaked this to be

declare
      cursor prodid_cursor is
      
      Select distinct product_id from product_relation where (relation_type = 5 or relation_type = 6 );

      cursor_row prodid_cursor%rowtype;
begin
      for cursor_row  in prodid_cursor
      loop
      Update Product_relation set reserved2 =
                  (select regioncode from group_product_att gp where gp.product_id = cursor_row.product_id and regioncode is not null) where  cursor_row.product_id = Product_relation.product_id;

      exception
      when others then
            dbms_output.put_line('Error: '||sqlerrm);      

      end loop;
      commit;
end;

It errors out saying with:
-------------------------------------------
ORA-06550: line 13, column 2:
PLS-00103: Encountered the symbol "EXCEPTION" when expecting one of the following:

   begin declare end exit for goto if loop mod null pragma raise
   return select update while <an identifier>
   <a double-quoted delimited-identifier> <a bind variable> <<
   close current delete fetch lock insert open rollback
   savepoint set sql execute commit forall
   <a single-quoted SQL string>
ORA-06550: line 18, column 2:
PLS-00103: Encountered the symbol "COMMIT" when expecting one of the following:

   begin function package pragma procedure form
The symbol "begin" was substituted for "COMMIT" to continue.
ORA-06550: line 20, column 0:
PLS-00103: Encountered the symbol "end-of-file" when expecting one of the following:

   begin function package pragma procedure form

-----------------------------------
If I pull the exception out of the loop and put it just before the commit, it prints out the exception clause and errors out and stops.

Can someone help me out. Thanks.