The call to display-results depends on the value of the current-namespace

parameter. Specifically, it is expected to be a namespace that has the GUI
bindings available. Unfortunately, during the dynamic extent of the
uncaught-exception-handler when a syntax error is raised, this may not be
the case because you get a phase 1 namespace, not a phase 0 one.

So, move the call to display-results to the code that runs the student language
programs and out of the uncaught exception handler.

collects/lang/htdp-langs.rkt

@@ -157,11 +157,6 @@
                  (namespace-require scheme-signature-module-name)
 		 ;; hack: the test-engine code knows about the test~object name; we do, too
 		 (namespace-set-variable-value! 'test~object (build-test-engine))
-		 (uncaught-exception-handler
-		  (let ((previous (uncaught-exception-handler)))
-		    (lambda (exc)
-		      (display-results)
-		      (previous exc))))
 		 ;; record signature violations with the test engine
 		 (signature-violation-proc
 		  (lambda (obj signature message blame)

collects/lang/run-teaching-program.rkt

@@ -57,7 +57,6 @@
                 #f
                 `(,#'module ,module-name ,language-module 
                             ,@(map (λ (x) `(require ,x)) teachpacks)
-                            ,@body-exps
                             ,@(if enable-testing?
                                   (if (null? body-exps)
                                       '() 
@@ -66,15 +65,14 @@
                                       ;; grabs a hold of this module to make a namespace for the REPL
                                       `(,(syntax-property
                                           #'(define test~object (namespace-variable-value 'test~object))
-					  'test-call #t)
-                                        (,#'test)))
-                                  '()))))
+                                          'test-call #t)))
+                                  '())
+                            ,@body-exps)))
               rep)))]
         [(require)
          (set! state 'done-or-exn)
          (stepper-syntax-property
-          (quasisyntax
-           (let ([done-already? #f])
+          #`(let ([done-already? #f])
               (dynamic-wind
                void
                (lambda () 
@@ -82,7 +80,10 @@
                (lambda () 
                  (unless done-already?
                    (set! done-already? #t)
-                  (current-namespace (module->namespace ''#,module-name)))))))
+                   #,(if enable-testing? 
+                         #'(test) 
+                         #'(begin))
+                   (current-namespace (module->namespace ''#,module-name))))))
           'stepper-skip-completely
           #t)]
         [(done-or-exn)