[luatex] Fatal error when removing nodelist's tail.

[Paul Isambert]

Hello all,

The following code produces a fatal error:

callback.register("ligaturing",
  function (head)
    node.remove(head, node.tail(last))
  end)

The error is:
! This can't happen (linebreak_tail).
!  ==> Fatal error occurred, no output PDF file produced!

The same happens in the "kerning" callback. It also happens even if you add
another node after the tail (and then remove the latter). I know the manual says
something about the tail of the list being recalculated, but I wouldn't expect
that removing the tail would cause an error. As far as I can tell, the error
happens at paragraph-building time (i.e. in "linebreak_filter").

Am I doing something wrong, or contemplating a bug?

Best,
Paul