--- a/devtools/client/inspector/inspector.js
+++ b/devtools/client/inspector/inspector.js
@@ -1401,17 +1401,18 @@ Inspector.prototype = {
     let content = clipboardHelper.getText();
     if (content && content.trim().length > 0) {
       return content;
     }
     return null;
   },
 
   _onContextMenu: function(e) {
-    if (e.originalTarget.closest("input[type=text]") ||
+    if (!(e.originalTarget instanceof Element) ||
+        e.originalTarget.closest("input[type=text]") ||
         e.originalTarget.closest("input:not([type])") ||
         e.originalTarget.closest("textarea")) {
       return;
     }
 
     e.stopPropagation();
     e.preventDefault();