refactor(Server): (attached_)sessions return list if server off

Author: tony

src/libtmux/server.py

@@ -207,7 +207,10 @@ def list_sessions(self) -> t.List[Session]:
     @property
     def sessions(self) -> t.List[Session]:
         """Property / alias to return :meth:`~.list_sessions`."""
-        return self.list_sessions()
+        try:
+            return self.list_sessions()
+        except Exception:
+            return []
 
     #: Alias :attr:`sessions` for :class:`~libtmux.common.TmuxRelationalObject`
     children = sessions  # type: ignore
@@ -348,7 +351,7 @@ def _update_panes(self) -> "Server":
         return self
 
     @property
-    def attached_sessions(self) -> t.Optional[t.List[Session]]:
+    def attached_sessions(self) -> t.List[Session]:
         """
         Return active :class:`Session` objects.
 
@@ -357,19 +360,22 @@ def attached_sessions(self) -> t.Optional[t.List[Session]]:
         list of :class:`Session`
         """
 
-        sessions = self._sessions
-        attached_sessions = list()
+        try:
+            sessions = self._sessions
+            attached_sessions = list()
 
-        for session in sessions:
-            attached = session.get("session_attached")
-            # for now session_active is a unicode
-            if attached != "0":
-                logger.debug("session %s attached", session.get("name"))
-                attached_sessions.append(session)
-            else:
-                continue
+            for session in sessions:
+                attached = session.get("session_attached")
+                # for now session_active is a unicode
+                if attached != "0":
+                    logger.debug("session %s attached", session.get("name"))
+                    attached_sessions.append(session)
+                else:
+                    continue
 
-        return [Session(server=self, **s) for s in attached_sessions] or None
+            return [Session(server=self, **s) for s in attached_sessions] or []
+        except Exception:
+            return []
 
     def has_session(self, target_session: str, exact: bool = True) -> bool:
         """