This feature added an internal interface that allows for creating
ephemeral "phantom" users, which help make nickname buttonizing possible
with protocol bridges and chat-history playback. Unfortunately, the
original design cut a major corner that it shouldn't have. Essentially,
I wanted to avoid adding an `erc-channel-user' to accompany every
phantom `erc-server-user' being spoofed, primarily because it's a waste
of space. However, I've come to believe this shortcut won't be worth the
added maintenance burden of having to check for missing objects when
performing related operations. Attached is a patch to fix this.