set term ^;

select cast('' as timestamp) from rdb$database
^
-- ERROR:
-- Statement failed, SQLSTATE = 22018
-- conversion error from string ""


recreate procedure qwe123
  returns(res timestamp)
as
begin
  res = cast('' as timestamp);
  suspend;
end
^

execute procedure qwe123
^
-- ERROR:
-- Statement failed, SQLSTATE = 22018
-- conversion error from string ""
-- At procedure 'QWE123' line: 5, col: 3

execute block
returns(res timestamp)
as
begin
  res = cast('' as timestamp);
  suspend;
end
^
-- ERROR:
-- Statement failed, SQLSTATE = 22018
-- conversion error from string ""

Something like "At anonymous block line: 5, col: 3" should be reported in this case.