Whether shouldShowBrowser will send src straight to the loader
without a network probe — a non-directory URL whose path names a store
(.zarr) or an archive (.zip). Synchronous, so bootstrap can start the
root-document fetch before app.init for exactly the URLs the loader is
certain to open, and never for one that may end in the dataset browser.
Whether shouldShowBrowser will send
srcstraight to the loader without a network probe — a non-directory URL whose path names a store (.zarr) or an archive (.zip). Synchronous, so bootstrap can start the root-document fetch beforeapp.initfor exactly the URLs the loader is certain to open, and never for one that may end in the dataset browser.