--- a/devtools/client/inspector/rules/rules.js
+++ b/devtools/client/inspector/rules/rules.js
@@ -821,17 +821,17 @@ CssRuleView.prototype = {
    *        Update the view even if the element is the same as last time.
    */
   selectElement: function(element, allowRefresh = false) {
     let refresh = (this._viewedElement === element);
     if (refresh && !allowRefresh) {
       return promise.resolve(undefined);
     }
 
-    if (this.popup.isOpen) {
+    if (this._popup && this.popup.isOpen) {
       this.popup.hidePopup();
     }
 
     this.clear(false);
     this._viewedElement = element;
 
     this.clearPseudoClassPanel();
     this.refreshAddRuleButtonState();