Address final code review feedback - improve comments and test mocking

Co-authored-by: mattcosta7 <8616962+mattcosta7@users.noreply.github.com>

Author: Copilot

src/lazy-define.ts

@@ -112,14 +112,15 @@ function scan(element: ElementLike) {
     // FIX 7: Early return optimization
     if (pending.size === 0) return
 
-    // FIX 7: Create snapshot to iterate safely
+    // FIX 7: Create snapshot to prevent modification-during-iteration issues
+    // (concurrent scans may delete tags from pending)
     const tagList = Array.from(pending.keys())
 
     for (const tagName of tagList) {
       const child: Element | null =
         element instanceof Element && element.matches(tagName) ? element : element.querySelector(tagName)
       if (customElements.get(tagName) || child) {
-        // Skip if already triggered and no longer in pending
+        // Skip if already processed and not re-registered
         if (triggered.has(tagName) && !pending.has(tagName)) continue
 
         triggered.add(tagName)
@@ -167,8 +168,9 @@ export function lazyDefine(tagNameOrObj: string | Record<string, () => void>, si
   }
 
   for (const [tagName, callback] of Object.entries(tagNameOrObj)) {
-    // FIX 6: Late registration - execute immediately if already triggered AND elements exist
-    if (triggered.has(tagName) && document.querySelector(tagName) !== null) {
+    // FIX 6: Late registration - execute immediately if already triggered
+    // Check both triggered state and element existence to avoid executing for removed elements
+    if (triggered.has(tagName) && document.querySelector(tagName)) {
       // eslint-disable-next-line github/no-then
       Promise.resolve().then(() => {
         try {

test/lazy-define.ts

@@ -1,5 +1,5 @@
 import {expect, fixture, html} from '@open-wc/testing'
-import {spy} from 'sinon'
+import {spy, stub} from 'sinon'
 import {lazyDefine, observe} from '../src/lazy-define.js'
 
 const animationFrame = () => new Promise<unknown>(resolve => requestAnimationFrame(resolve))
@@ -161,10 +161,8 @@ describe('lazyDefine', () => {
       })
       const onDefine2 = spy()
 
-      // Suppress global error reporting for this test
-      const originalReportError = globalThis.reportError
       const errors: unknown[] = []
-      globalThis.reportError = (err: unknown) => errors.push(err)
+      const reportErrorStub = stub(globalThis, 'reportError').callsFake((err: unknown) => errors.push(err))
 
       try {
         lazyDefine('error-test-element', onDefine1)
@@ -180,7 +178,7 @@ describe('lazyDefine', () => {
         // Error should have been reported
         expect(errors.length).to.be.greaterThan(0)
       } finally {
-        globalThis.reportError = originalReportError
+        reportErrorStub.restore()
       }
     })
   })