OpenRA

System.ArgumentNullException: Value cannot be null.
Parameter name: stream
at System.IO.StreamReader..ctor(Stream stream, Encoding encoding, Boolean detectEncodingFromByteOrderMarks, Int32 bufferSize)
at System.IO.StreamReader..ctor(Stream stream)
at OpenRA.FileFormats.MiniYaml.FromStream(Stream s)
at OpenRA.FileFormats.MapStub..ctor(IFolder package)
at OpenRA.ModData.<FindMaps>m__108(String p)
at System.Linq.Enumerable.WhereSelectListIterator`2.MoveNext()
at System.Linq.Enumerable.ToDictionary[TSource,TKey,TElement](IEnumerable`1 source, Func`2 keySelector, Func`2 elementSelector, IEqualityComparer`1 comparer)
at System.Linq.Enumerable.ToDictionary[TSource,TKey](IEnumerable`1 source, Func`2 keySelector)
at OpenRA.ModData.FindMaps(String[] mods)
at OpenRA.ModData..ctor(String[] mods)
at OpenRA.Game.Initialize(Arguments args)
at OpenRA.Program.Run(String[] args)
at OpenRA.Program.Main(String[] args)