fix(runtime): skip native attribute watchers until the lazy instance exists

[addahlbe]

What is the current behavior?

With the lazy loader, a component that uses @Watch on a native (non-@Prop) attribute throws from attributeChangedCallback when that attribute changes after the element connects but before the component's module has loaded:

TypeError: Cannot read properties of undefined (reading 'ariaLabelChanged')

The propName == null branch only checks hostRef.$flags$, which already includes hasConnected at that point, while hostRef.$lazyInstance$ is still undefined.

GitHub Issue Number: #6945

What is the new behavior?

The watcher lookup is null-safe (instance?.[watchMethodName]), so a change that arrives before the instance exists is ignored. That matches @Prop changes, which don't fire watchers before the component is ready either. Changes after the instance exists still reach the watcher.

Documentation

N/A

Does this introduce a breaking change?

• Yes
• No

Testing

• Added a newSpecPage test in src/runtime/test/watch.spec.tsx. It connects a component with @Watch('aria-label'), sets aria-label before the module is flushed, and expects no error. After waitForChanges() it sets the attribute again and expects the watcher to receive it.
• Without the fix the test fails with TypeError: Cannot read properties of undefined (reading 'ariaLabelChanged'). With the fix it passes.
• jest src/runtime: 65 suites, 684 tests pass. eslint and prettier --list-different are clean on both files.
• Manually checked in Chrome with a minimal www build of the component from bug: changing a watched native attribute before a lazy component's instance exists throws #6945. On 4.45.2 the page logs the uncaught TypeError. Built against this branch, there is no error, and a later setAttribute logs ariaLabelChanged after load.

Other information

We hit this in production through Ionic, where ion-button watches aria-label, aria-pressed and aria-checked and an Angular [attr.aria-label] binding can update the attribute before the button's chunk loads.

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