fix js crash

modules/js.js

@@ -13,9 +13,11 @@ var js = function(dbot) {
     var commands = {
         // Run JS code sandboxed, return result to channel.
         '~js': function(event) {
+            try {
                 s.run(event.input[1], function(output) {
                     event.reply(output.result);
                 }.bind(this));
+            } catch(err) {}
         },
 
         // Run JS code un-sandboxed, with access to DBot memory (admin-only).