Disallow starting a game without players

OpenRA.Mods.Common/ServerTraits/LobbyCommands.cs

@@ -33,6 +33,9 @@ namespace OpenRA.Mods.Common.Server
 		[TranslationReference]
 		static readonly string NoStartUntilRequiredSlotsFull = "no-start-until-required-slots-full";
 
+		[TranslationReference]
+		static readonly string NoStartWithoutPlayers = "no-start-without-players";
+
 		[TranslationReference]
 		static readonly string TwoHumansRequired = "two-humans-required";
 
@@ -252,6 +255,10 @@ namespace OpenRA.Mods.Common.Server
 				if (server.LobbyInfo.Slots.Any(sl => sl.Value.Required && server.LobbyInfo.ClientInSlot(sl.Key) == null))
 					return;
 
+				// Don't start without any players
+				if (server.LobbyInfo.Slots.All(sl => server.LobbyInfo.ClientInSlot(sl.Key) == null))
+					return;
+
 				if (LobbyUtils.InsufficientEnabledSpawnPoints(server.Map, server.LobbyInfo))
 					return;
 
@@ -296,6 +303,12 @@ namespace OpenRA.Mods.Common.Server
 					return true;
 				}
 
+				if (server.LobbyInfo.Slots.All(sl => server.LobbyInfo.ClientInSlot(sl.Key) == null))
+				{
+					server.SendOrderTo(conn, "Message", NoStartWithoutPlayers);
+					return true;
+				}
+
 				if (!server.LobbyInfo.GlobalSettings.EnableSingleplayer && server.LobbyInfo.NonBotPlayers.Count() < 2)
 				{
 					server.SendLocalizedMessageTo(conn, TwoHumansRequired);

OpenRA.Mods.Common/Widgets/Logic/Lobby/LobbyLogic.cs

@@ -383,6 +383,7 @@ namespace OpenRA.Mods.Common.Widgets.Logic
 			{
 				startGameButton.IsDisabled = () => configurationDisabled() || map.Status != MapStatus.Available ||
 					orderManager.LobbyInfo.Slots.Any(sl => sl.Value.Required && orderManager.LobbyInfo.ClientInSlot(sl.Key) == null) ||
+					orderManager.LobbyInfo.Slots.All(sl => orderManager.LobbyInfo.ClientInSlot(sl.Key) == null) ||
 					(!orderManager.LobbyInfo.GlobalSettings.EnableSingleplayer && orderManager.LobbyInfo.NonBotPlayers.Count() < 2) ||
 					insufficientPlayerSpawns;