Workaround 2
------------
Declare an empty parameter list, and reference this in the RUN_PRODUCT call:
DECLARE p_id ParamList;
BEGIN
RUN_PRODUCT( REPORTS, 'empreport', SYNCHRONOUS, RUNTIME, FILESYSTEM, p_id, NULL );
END;

Workaround 3
------------
Use '', instead of NULL:
RUN_PRODUCT( REPORTS, 'empreport', SYNCHRONOUS, RUNTIME, FILESYSTEM, '', NULL );

The sixth argument is an empty string; hence, it is of datatype VARCHAR2, which tells Oracle Forms to expect a parameter list name.

Workaround 4
------------
Use named notation:
RUN_PRODUCT( REPORTS, 'empreport', SYNCHRONOUS, RUNTIME, FILESYSTEM, paramlist_name=>NULL, display=>NULL );