Else if does not work

[Alex-Lord1]

This code is taken from the Stylus documentation

compare(a, b)
  if a > b
    higher
  else if a < b
    lower
  else
    equal

It causes an error "Found an input node of undefined, which had a parent node of {"__type":"If","cond":{"__type":"Expression","lineno":4,"column":15,"filename":null,"nodes":[{"__type":"Expression","lineno":4,"column":15,"filename":null,"nodes":[{"__type":"BinOp","left":{"__type":"Ident","name":"a","val":{"__type":"Null"},"mixin":false,"lineno":4,"column":8,"filename":null},"right":{"__type":"Ident","name":"b","val":{"__type":"Null"},"mixin":false,"lineno":4,"column":13,"filename":null},"op":"<","lineno":4,"column":15,"filename":null}]}]},"elses":[],"negate":{"__type":"Block","scope":false,"lineno":4,"column":15,"filename":null,"nodes":[{"__type":"Ident","name":"lower","val":{"__type":"Null"},"mixin":false,"lineno":4,"column":16,"filename":null}]},"lineno":5,"column":8,"filename":null}"

If you remove

  else if a < b
    lower

Then everything works