The same. It does strlen(0) somewhere

  $ dtrace -n 'pid$target::strlen:entry { print(arg0) }' -c './a.out 2'
  CPU     ID                    FUNCTION:NAME
  ⋮
    4  22139                     strlen:entry int64_t 0

It requires a file with a nonblank first line. I'm working on that...

Did you give it a file to edit on the cmd line?