I consider this a “blunder” (bug) although I’m sure it made sense to someone. In a program without line numbers the line number reported in errors seems to be one greater than the count of all executable lines (not blank or remark only) up to and including the failing line. So people don’t have to go nuts figuring out where the error is it should report the literal 1 based line number of the incoming file to match what the editor is showing and looking for.