[Lazarus] App crash at TScreen.GetCustomFormsZOrdered

[Petr Hlozek]

Hi,

I have an Linux app, it has over 76k lines of code, 78 Forms and uses threads.
After I close the app, it always crashes in

function TScreen.GetCustomFormsZOrdered(Index: Integer): TCustomForm;
begin
  Result := TCustomForm(FCustomFormsZOrdered[Index]);
end;

The index variable value is something like 42325 or so.
I tried to debug and here is what I found out:

It goes through all FormCloseQuesry, FormDestroy and
DatamoduleDestory, then it goes to
TApplication.DoBeforeFinalization and then into
TScreen..GetCustomFormsZOrdered where it fails.
I spent days trying to find out where could be the problem but didn't
find anything. I'm lost. Do you have any idea where could be a
problem, please? Thanks a lot!

Petr