return None if no display present

src/component/component.js

@@ -132,7 +132,10 @@ class pdbLigandEnv extends LitElement {
   }
 
   set zoom(data) {
-    if (this.display !== undefined) this.display.toggleZoom(data);
+    if (!this.display){
+      return
+    }
+    this.display.toggleZoom(data);
   }
 
   set atomNames(data) {