recreate table t (id int, f2 char(16));
commit;

insert into t values (1, '0123456798012345');
insert into t values (2, '0123456798012345');
commit;

alter table t drop f2;
commit;

update t set id = 3 where id = 2;
commit;

execute block returns (id int)
as
begin
  select t1.id from t t1 left join t t2 on t1.id = t2.id - 2
   where t2.id = 3
    into :id;
  suspend;
end

Last statement produced bugcheck :

internal Firebird consistency check (cannot restore singleton select data (284), file: rse.cpp line: 3360)