Parser treats indentation sensitive syntax wrongly

[skingo]

The simple_nested.ub example fails after destructorizing Stream, since all "trailing" cocases are always added to the last seen comatch instead of the correct on (i.e. the one with the same indentation).
As a workaround, one can add id functions around local xtors, which has the side effect of surrounding the resulting xmatches by parentheses, thus making them parse correctly.

data Bool where
   True()
   False()

codata Stream where
   s() : Stream
   s2() : Stream

fun id(x0 : Stream) : Stream :=
   x0



gfun Simpl() : Stream :=
   cocase s() => Simpl()
   cocase s2() => id(comatch L2  with
      cocase s() => id(comatch L1  with
         cocase s() => id(comatch L3  with
            cocase s() => Simpl()
            cocase s2() => Simpl())
         cocase s2() => Simpl())
      cocase s2() => Simpl())