We no longer need to avoid IO or worry about exceptions, so drop the with-handlers.

Revert "This is a change to paper over a bug elsewhere in the system that threatens the release."

This reverts commit 25adab8cbb.

collects/lang/htdp-langs.rkt

@@ -439,8 +439,7 @@
           
           (define/override (first-opened settings)
             (for ([tp (in-list (htdp-lang-settings-teachpacks settings))])
-              (with-handlers ((exn:fail? void))
-                (namespace-require/constant tp))))
+              (namespace-require/constant tp)))
           
           (inherit get-module get-transformer-module get-init-code
                    use-namespace-require/copy?)