Don't hide a node if its children are still loading

[ErikSom]

In the following video you can see the tiles being removed before its children are loaded. I have exaggerated the issue by introducing an additional timeout in the tile renderer loader:

    const load = async (node) => {
        const uri = node.content.uri;
        console.log('LOADING: ' + uri);
        const url = `${this.apiUrl}${uri}?key=${apiKey}&session=${this.tileManager.session}`;

        /** @type {pc.Asset} */
        let asset;
        try {
            asset = await this.loadGlb(url);
        } catch (err) {
            console.error("An error occurred while loading the GLB:", err);
        }

        await new Promise(r => setTimeout(r, 5000));

earthatile-tile-popping-issue.mov

The problem; if a node contained GLB content but its children contained JSON, it would be removed after the JSON got loaded and not after the actual new child mesh is loaded.

I solve this by introducing a dependency, there could possibly be a better way to solve it, but for now this works for me.
Here you can see the fix in action:

earthatile-tile-popping-fix.mov

[willeastcott]

Comment seems unfinished.