The implicit version of for..in comprehension (the version without the in keyword) causes compilation error on line, where the in keyword is used, and is on the same depth. And by depth I don't mean indent, it is something different, something internal.

Minimal example:

[1 for a]
[b in c]

Extended example, with diverse ways of increasing the depth:

[[{b: {[.., 1] for a}}]]
->
  if c
    d
      .e (.f in [2 3])

I noticed, that only comprehensions are affected by this bug, and only those without the in keyword.
The construction for a => .. doesn't cause an error.

The in expression also has to be somehow wrapped. This:

[1 for a]
->
  b in c

is not erroneous.