Make sure we always have a game type when we ask for it (ddnet#11635)

Author: Robyt3

src/game/server/gamecontext.cpp

@@ -4712,7 +4712,12 @@ bool CGameContext::IsClientHighBandwidth(int ClientId) const
 }
 
 CUuid CGameContext::GameUuid() const { return m_GameUuid; }
-const char *CGameContext::GameType() const { return m_pController && m_pController->m_pGameType ? m_pController->m_pGameType : ""; }
+const char *CGameContext::GameType() const
+{
+	dbg_assert(m_pController, "no controller");
+	dbg_assert(m_pController->m_pGameType, "no gametype");
+	return m_pController->m_pGameType;
+}
 const char *CGameContext::Version() const { return GAME_VERSION; }
 const char *CGameContext::NetVersion() const { return GAME_NETVERSION; }