Increase error verbosity when import fails

[eddie-knight]

The current error "unsupported scheme" isn't inherently clear without referring to the layer 2 codebase.

$ go run . yaml -t storage/object

----------------------------------------

     _______________
    / ___/ ___/ ___/
   / /  / /  / / 
  / /__/ /__/ /___ 
  \____/____/____/

2025/09/08 08:51:33 error loading content for ../catalogs/storage/object: unsupported scheme: 
exit status 1