This is necessary for the upcoming comprehension changes. Because comprehensions are possibly computed later in the new algorithm, special care should be taken that the first closedness check is done after comprehensions are computed. This introduces some stutter in error messages that will be removed in another CL later. Change-Id: Icdebc96dde707815fb0f5b6b5fa13d28cff6a196 Signed-off-by: Marcel van Lohuizen <mpvl@golang.org> Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/532833 Reviewed-by: Marcel van Lohuizen <mpvl@gmail.com>