diff --git a/node_modules/ace/lib/ace/lib/lang.js b/node_modules/ace/lib/ace/lib/lang.js
index f306e3e4..ab3d4d51 100644
--- a/node_modules/ace/lib/ace/lib/lang.js
+++ b/node_modules/ace/lib/ace/lib/lang.js
@@ -74,7 +74,7 @@ exports.copyArray = function(array){
     var copy = [];
     for (var i=0, l=array.length; i<l; i++) {
         if (array[i] && typeof array[i] == "object")
-            copy[i] = this.copyObject( array[i] );
+            copy[i] = this.copyObject(array[i]);
         else 
             copy[i] = array[i];
     }
@@ -92,14 +92,12 @@ exports.deepCopy = function deepCopy(obj) {
         }
         return copy;
     }
-    var cons = obj.constructor;
-    if (cons === RegExp)
+    if (Object.prototype.toString.call(obj) !== "[object Object]")
         return obj;
     
-    copy = cons();
-    for (var key in obj) {
+    copy = {};
+    for (var key in obj)
         copy[key] = deepCopy(obj[key]);
-    }
     return copy;
 };
 
diff --git a/plugins/c9.fs/fs.cache.xml.js b/plugins/c9.fs/fs.cache.xml.js
index 9d2a6c6d..9d0babbe 100644
--- a/plugins/c9.fs/fs.cache.xml.js
+++ b/plugins/c9.fs/fs.cache.xml.js
@@ -629,6 +629,14 @@ define(function(require, exports, module) {
                     });
                 } else if (key === "children" || key === "isSelected") {
                     prop = null;
+                } else if (Object.prototype.toString.call(node[key]) == "[object Date]") {
+                    // why Date ends up here?
+                    reportError(new Error("Date in fs cache"), {
+                        key: key,
+                        value: node[key],
+                        path: node.path,
+                        hasParentProp: !!node.parent,
+                    });
                 } else {
                     prop = lang.deepCopy(node[key]);
                 }
@@ -637,9 +645,9 @@ define(function(require, exports, module) {
             return copy;
         }
         
-        function clear(){
+        function clear() {
             var all = model.visibleItems;
-            for (var i = all.length; i--; ) {
+            for (var i = all.length; i--;) {
                 if (model.isOpen(all[i]))
                     model.collapse(all[i]);
             }