Prevent comments from being processed when selected in the layers tree.

src/commands/view/ShowOffset.ts

@@ -18,6 +18,10 @@ export default {
     const zoom = this.em.getZoomDecimal();
     const el = opt.el as HTMLElement | undefined;
 
+    // if (!(el instanceof HTMLElement)) {
+    //   return;
+    // }
+
     if (!config.showOffsets || !el || isTextNode(el) || (!config.showOffsetsSelected && state == 'Fixed')) {
       editor.stopCommand(`${this.id}`, opts);
       return;

src/utils/dom.ts

@@ -37,6 +37,9 @@ export const attrUp = (el?: HTMLElement, attrs: ObjectAny = {}) =>
   el && el.setAttribute && each(attrs, (value, key) => el.setAttribute(key, value));
 
 export const isVisible = (el?: HTMLElement) => {
+  if (!el || !(el instanceof HTMLElement)) {
+    return false;
+  }
   return el && !!(el.offsetWidth || el.offsetHeight || el.getClientRects().length);
 };