Warning.hs is not listed in the html-entity.cabal and is therefore missing from hackage

[stepcut]

As a result, if you choose to build without doctest it dies with,

[1 of 1] Compiling Main             ( Setup.hs, /private/var/folders/_b/wj7ns2190gd3hbz9w0f3m17c0000gn/T/nix-build-html-entity-0.1.3.0.drv-0/Main.o )

Setup.hs:13:1: error:
    Could not find module ‘Warning’
    Use -v to see a list of the files searched for.
   |
13 | import Warning ()
   | ^^^^^^^^^^^^^^^^^