Deepcopy patch

some things can't be copied... what to do

js/utils.js

@@ -750,13 +750,34 @@ function assert_error(func_binding, msg) {
 /**
  * Deep copy object/array of basic types.
  */
-function deepcopy(obj) {
+function deepcopy(obj, refs=undefined) {
+    if (refs === undefined) {
+        refs = new Map();
+    }
     if (typeof(obj) !== 'object' || obj === null) { // null or value type
         return obj;
     }
     let ret = Array.isArray(obj) ? [] : {};
     for (let key in obj) {
-        ret[key] = deepcopy(obj[key]);
+        let val;
+        try {
+            val = obj[key];
+        } catch (exc) {
+            console.trace();
+            val = undefined;
+        }
+        if (typeof(obj) === 'object') {
+            if (refs.has(val)) {
+                ret[key] = refs.get(val);
+            }
+            else {
+                refs.set(val, val);
+                ret[key] = deepcopy(val, refs);
+            }
+        }
+        else {
+            ret[key] = val;
+        }
     }
     return ret;
 }