Impossible to drop function in package with name of PSQL-function

[CyberMaxRu]

Firebird 4.0.2.2770.

1. Create objects.

CREATE OR ALTER FUNCTION SOME_FUNC
RETURNS INTEGER
AS
BEGIN
RETURN 1;
END

SET TERM ^ ;

CREATE OR ALTER PACKAGE TEST_PKG
AS
BEGIN
FUNCTION SOME_FUNC() RETURNS INTEGER;-- Same name of real function, but in package
END^

RECREATE PACKAGE BODY TEST_PKG
AS
BEGIN
FUNCTION SOME_FUNC() RETURNS INTEGER
AS
BEGIN
END
END^

SET TERM ; ^

CREATE OR ALTER PROCEDURE TEST_PROC
AS
DECLARE VARIABLE NEW_INT INTEGER;
BEGIN
:NEW_INT = SOME_FUNC();
END

2. Used PSQL-function, function in package no need, drop it:

CREATE OR ALTER PACKAGE TEST_PKG
AS
BEGIN
-- FUNCTION SOME_FUNC() RETURNS INTEGER;
END

Error:
This operation is not defined for system tables.
unsuccessful metadata update.
cannot delete.
Function SOME_FUNC.
there are 1 dependencies.

SQLCODE: -607
SQLSTATE: 38000
GDSCODE: 335544351