Raised instead of dropping the option. The Python sibling warns and carries on, which returns a pane that differs from the one described in a way nothing downstream can detect; a caller who asked for an empty pane and got a shell has no way to notice before something runs in it.
Its own type so a caller who can do without the feature can catch exactly this, rather than matching on a message. The feature and the versions are in the message and not in accessors: a throwable is serializable, so exposing a {@link TmuxVersion} here would mean making that serializable too, and no caller has needed to read them apart from the text. ## Members - `UnsupportedTmuxVersion` (method) — For a capability that is missing from a range rather than from everything before a release.