This is a response to the message of Lars. Apparently, we get the same backtrace.

```

Debugger entered--Lisp error: (error "Negative repetition argument -1")
  self-insert-command(-1)
  newline(-1)
  open-line(-1)
  eval((open-line -1) t)
  eval-expression((open-line -1) nil nil 127)
  funcall-interactively(eval-expression (open-line -1) nil nil 127)
  call-interactively(eval-expression nil nil)
  command-execute(eval-expression)

```

This is what C-h f open-line RET shows

```

open-line is an interactive compiled Lisp function in ‘simple.el’.

It is bound to C-o, <insertline>.

(open-line N)

  Probably introduced at or before Emacs version 19.29.

Insert a newline and leave point before it.
If there is a fill prefix and/or a ‘left-margin’, insert them on
the new line if the line would have been blank.
With arg N, insert N newlines.

```