error.Error.LinkGone

Distinct from Self::ObjectGone , and the distinction decides whether a caller may discard a handle: the object may be perfectly alive, linked into another session or sitting at another index. What is known is only that this target resolved to nothing.

tmux answers a missing target by echoing it back, and the echo settles which of the two happened for some target forms and not others. A coordinate -- an index, or a window name, written session:index -- is scoped to one session and is not unique on the server, so its absence is always this error and never the other. An identity carries its kind's sigil (@ a window, % a pane) and echoes identically whether the object died or merely lives under another session's link, so telling those apart costs a lookup and belongs to the caller that can afford one.

Self::is_object_gone answers false: a handle whose object is still running must not be dropped on this evidence.