1 files changed, 4 insertions, 3 deletions
diff --git a/lib/js/urweb.js b/lib/js/urweb.js
index ba73e744..adab5f43 100644
--- a/lib/js/urweb.js
+++ b/lib/js/urweb.js
@@ -643,9 +643,10 @@ function parent() {
 }
 
 function addNode(node) {
-    if (thisScript)
-        thisScript.parentNode.replaceChild(node, thisScript);
-    else
+    if (thisScript) {
+        if (thisScript.parentNode)
+            thisScript.parentNode.replaceChild(node, thisScript);
+    } else
         lastParent().appendChild(node);
 }