libtmux(fix[logging]): guard None values in server/session extra dicts

why: session_id and session_name can be None (str | None), violating
the logging standard that extra values must be str at INFO+ level.
what:
- session.py rename_session: use conditional-build pattern for tmux_target
- server.py new_session DEBUG log: conditional tmux_session
- server.py new_session INFO log: conditional tmux_session

Author: tony

src/libtmux/server.py

@@ -538,13 +538,12 @@ def new_session(
                         msg,
                     )
 
-        logger.debug(
-            "creating session",
-            extra={
-                "tmux_session": session_name,
-                "tmux_subcommand": "new-session",
-            },
-        )
+        extra: dict[str, str] = {
+            "tmux_subcommand": "new-session",
+        }
+        if session_name is not None:
+            extra["tmux_session"] = str(session_name)
+        logger.debug("creating session", extra=extra)
 
         env = os.environ.get("TMUX")
 
@@ -600,13 +599,12 @@ def new_session(
 
         session = Session(server=self, **session_data)
 
-        logger.info(
-            "session created",
-            extra={
-                "tmux_subcommand": "new-session",
-                "tmux_session": session.session_name,
-            },
-        )
+        info_extra: dict[str, str] = {
+            "tmux_subcommand": "new-session",
+        }
+        if session.session_name is not None:
+            info_extra["tmux_session"] = str(session.session_name)
+        logger.info("session created", extra=info_extra)
 
         return session
 

src/libtmux/session.py

@@ -439,14 +439,13 @@ def rename_session(self, new_name: str) -> Session:
 
         self.refresh()
 
-        logger.info(
-            "session renamed",
-            extra={
-                "tmux_subcommand": "rename-session",
-                "tmux_session": new_name,
-                "tmux_target": self.session_id,
-            },
-        )
+        extra: dict[str, str] = {
+            "tmux_subcommand": "rename-session",
+            "tmux_session": new_name,
+        }
+        if self.session_id is not None:
+            extra["tmux_target"] = str(self.session_id)
+        logger.info("session renamed", extra=extra)
 
         return self