add check for depiction before triggering external events

src/plugin/manager.ts

@@ -124,6 +124,7 @@ class Visualization {
     }
 
     private ligHeatmapMouseoverEventHandler(e: any) {
+        if (this.depiction === undefined) return;
         const atomName = e.detail.name; // CustomEvent
         const atom = this.depiction.atoms.filter(x => x.value >0 && x.name === atomName);
         if (atom.length > 0) {
@@ -134,6 +135,7 @@ class Visualization {
     }
 
     private ligHeatmapMouseoutEventHandler() {
+        if (this.depiction === undefined) return;
         this.depiction.atomMouseLeaveEventHandler(true);
     }