Delaration of package constant in form "CONSTANT foo int = NULL" crashes FB.

[Pavel Zotov]

0) FB snapshot: 6.0.0.1965-f9a8d1a

1) firebird.conf:

BugCheckAbort = 1
RemoteServicePort = 3600
IpcName = C__FB_60SS

2) SQL:

================

set bail on;
set autoterm on;
set list on;
set echo on;
shell if exist r:\temp\tmp4test.fdb del r:\temp\tmp4test.fdb;
create database 'localhost:r:\temp\tmp4test.fdb' user sysdba password 'masterkey';
 
create or alter package pg_const_null as
begin
    constant bar int = null;
end
;

================

Result:
FB crashes.

URL to dump, BT, snapshot, config and log:

https://drive.google.com/drive/folders/1rZIn-KR32SK-wmPyI7EheMb042sS8_qN?usp=sharing