Autoconfigured BLS actions use "$root\\$initrd" as the initrd path.
For BLS entries without an initrd line this stamps to the root of the
filesystem, and Sprout tried to read that directory as the initrd,
failing the boot. Treat a path that resolves to no file as no initrd.
The chainload action held the child image's LoadedImage protocol open
exclusively while calling start_image. Any image that opens its own
LoadedImage protocol exclusively, such as another uefi-rs application
or Sprout itself, then failed with ACCESS_DENIED. Scope the protocol to
setting the load options.