Flash-of-front-page before loading global page component by slug

[cstephen]

This is an issue that affects the webapp in production while built & hosted from an S3 bucket, but does not affect the webapp locally (at least not while running via npm run dev).

If you visit any part of the webapp that loads a page component based on the slug name (any item in components/global basically, including all data x-ray items and data stories), there's a brief moment where the front page of the webapp is displayed before the component is loaded. It would be better if the webapp showed the "Loading ARDAC" screen instead of the front page while the global component is loading, and never shows the front page at all.

This behavior is especially bad for any ARDAC item that loads the Gimme component with the extent property set and needs to determine if communities fall within a GeoJSON extent before loading. With the additional international communities added for the pan-Arctic CMIP6 dataset, this process takes longer than it used to, and the flash-of-front-page is conspicuously long. See this page for example: https://arcticdatascience.org/item/permafrost-talik If users saw the "Loading ARDAC" screen instead of the front page, this wouldn't be as strange.