500 error when attempting to GET a cookbook artifact ACL for invalid artifact

This is easily reproduceable against current hosted chef:

$ bin/knife raw cookbook_artifacts/bad_artifact
ERROR: Server responded with error 404 "Object Not Found"
ERROR: Error Body: {"error":["not_found"]}
?1 chef/knife $ bin/knife raw cookbook_artifacts/bad_artifact/_acl
ERROR: Server returned error 500 for https://api.chef.io/organizations/jiminywarehouse/cookbook_artifacts/bad_artifact/_acl, retrying 1/5 in 4s

The fix for this is to add a handler to chef_wm_util:not_found_message, as

chef_wm_util:not_found_message(cookbook_artifact, Name)

The dialyzer spec must also be updated to indicated cookbook_artifact is an accepted input. It is worth looking too to see why dialyzer didn't warn/error about this function being called with non-matching input - maybe something in the existing rule is too general and needs to be tightened up.

https://github.com/chef/chef-server/blob/dbc44702778cf74a833d738ef1a9e0de12e14b93/src/oc_erchef/apps/oc_chef_wm/src/chef_wm_util.erl#L114-L163

Aha! Link: https://chef.aha.io/features/SH-3015