Merge #4225

4225: Fix segfault when joining team (fixes #4224) r=Zwelf a=def-

<!-- What is the motivation for the changes of this pull request -->

## Checklist

- [x] Tested the change ingame
- [ ] Provided screenshots if it is a visual change
- [ ] Tested in combination with possibly related configuration options
- [ ] Written a unit test if it works standalone, system.c especially
- [ ] Considered possible null pointers and out of bounds array indexing
- [ ] Changed no physics that affect existing maps
- [ ] Tested the change with [ASan+UBSan or valgrind's memcheck](https://github.com/ddnet/ddnet/#using-addresssanitizer--undefinedbehavioursanitizer-or-valgrinds-memcheck) (optional)


Co-authored-by: def <dennis@felsin9.de>

src/game/server/gamecontext.cpp

@@ -765,6 +765,9 @@ void CGameContext::SendTuningParams(int ClientID, int Zone)
 
 void CGameContext::OnPreTickTeehistorian()
 {
+	if(!m_TeeHistorianActive)
+		return;
+
 	auto *pController = ((CGameControllerDDRace *)m_pController);
 	for(int i = 0; i < MAX_CLIENTS; i++)
 	{