When we determine that current cache keys are to be discarded, we
should also discard the associated members for correctness. This
should act as a safeguard against accessing Artifact instances that
have discarded cache keys.

A side effect of this is the querying of element buildtree state
from cli methods on elements that don't have a cached artifact
would lead to the artifact member methods not being reachable.
Ensuring the element is cached before trying to call said accessor
methods resolves this.