Fix some tests (and remove Knock tests)

Author: jmct

langs/loot/compile.rkt

@@ -526,7 +526,7 @@
 ;; Id CEnv -> Integer
 (define (lookup x cenv)
   (match cenv
-    ['() (error "undefined variable:" x " Env: " cenv)]
+    ['() (error (~a "undefined variable:" x " Env: " cenv))]
     [(cons y rest)
      (match (eq? x y)
        [#t 0]

langs/loot/test/test-runner.rkt

@@ -104,16 +104,6 @@
                                (+ x (tri (sub1 x)))))
                          (tri 9)))
                 45)
-  ;; Knock tests
-  (check-equal? (run
-                  '(begin (define (f x) x)
-                          (call (fun f) 42)))
-                42)
-  (check-equal? (run
-                  '(begin (define (f x) x)
-                          (define (g x) x)
-                          (call (car (cons (fun f) (cons (fun g) '()))) 42)))
-                42)
 #|
   (check-equal? (run
                  '(begin (define (even? x)