Return value to shell on errors is not always set.

[ecraven]

Playing around with huskc/huski I noticed that when an error occurs, the return value to the shell is still sometimes 0, so it isn't possible to reliably detect errors.
Example code to trigger this:

(import (scheme base))
(define (assert x) (unless x (error "ERROR assertion failed")))
(assert (equal? '#1=(a b . #1#) '#2= (a b a b . #2#)))

or

(import (scheme base) (scheme list))
(define (assert x) (unless x (error "ERROR assertion failed")))
(assert (equal? 1 1))

run with huski /tmp/test.scm, this produces error output as follows, but doesn't actually set the return value to anything other than 0:

Parse error at : "lisp" (line 3, column 19):
unexpected "1"

or

Error: File does not exist: scheme/list.sld

All the error messages are different, so there is no way to check for that either :-/