fix(core): optional chaining on renderer state as it can be null during nullifying state of previous object downstream

The custom materials were erroring out because we nullifying previous
object renderer state in a computed. That happens BEFORE *args receives
the new computed and destroy the ref.

Author: nartc

libs/core/src/lib/renderer/index.ts

@@ -288,7 +288,7 @@ export class NgtRenderer implements Renderer2 {
 	removeChild(parent: NgtRendererNode | null, oldChild: NgtRendererNode, isHostElement?: boolean | undefined): void {
 		if (parent == null) {
 			parent = (untracked(() => getLocalState(oldChild)?.parent?.()) ||
-				oldChild.__ngt_renderer__[NgtRendererClassId.parent]) as NgtRendererNode;
+				oldChild.__ngt_renderer__?.[NgtRendererClassId.parent]) as NgtRendererNode;
 		}
 
 		const cRS = oldChild.__ngt_renderer__;