That was the wrong fix. MSG_ERROR should set the error and the client should

use the error and exit on MSG_EXIT (it was being handled in the default
case). Undo the last change, move the errstr check into the MSG_EXIT case, and
add a comment.

tmux.h

@@ -973,8 +973,7 @@ struct client_ctx {
 		CCTX_DETACH,
 		CCTX_EXIT,
 		CCTX_DIED,
-		CCTX_SHUTDOWN,
-		CCTX_ERROR
+		CCTX_SHUTDOWN
 	} exittype;
 	const char	*errstr;
 };