Better recovery with problem icons (was Creating world: `The given key '1699' was not present in the dictionary.`)

[misterbeebee]

After launching the game and choosing nation, number of AI, etc, the app crashes with this exception.

1. I suspect it's something to do with failing to load the original Civ art assets, but I don't see where to input the path to assets -- I think the app prompted for that once in the past, and I don't know where to change it.

2. If there is a known cause for this error, it would be good if the error message gave useful advice..

The error is in SetIcon, trying to load data from LZW-compressed image file:

		protected void SetIcon(char page, int col, int row)
		{
			if (_iconCache[(int)Type] == null)
			{
--->				_iconCache[(int)Type] = Resources[$"ICONPG{page}"][col * 160, row * 62, 160, 60]
					.ColourReplace((byte)(GFX256 ? 253 : 15), 0);
			}
			Icon = _iconCache[(int)Type];
		}

Unhandled Exception: System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.Collections.Generic.KeyNotFoundException:
The given key '1699' was not present in the dictionary.
   at System.Collections.Generic.Dictionary`2.get_Item(TKey key)
   at CivOne.IO.LZW.Decode(Byte[] input, Boolean clearEnd, Boolean flushDictionary, Int32 minBits, Int32 maxBits) in E:\proj\CivOneMaster\src\IO\LZW.cs:line 81
   at CivOne.Graphics.ImageFormats.PicFile.DecodePicture(Int32& index, UInt32 length) in E:\proj\CivOneMaster\src\Graphics\ImageFormats\PicFile.cs:line 124
   at CivOne.Graphics.ImageFormats.PicFile.ReadPictureX0(Int32& index) in E:\proj\CivOneMaster\src\Graphics\ImageFormats\PicFile.cs:line 138
   at CivOne.Graphics.ImageFormats.PicFile..ctor(String filename) in E:\proj\CivOneMaster\src\Graphics\ImageFormats\PicFile.cs:line 333
   at CivOne.Graphics.Resources.get_Item(String filename) in E:\proj\CivOneMaster\src\Graphics\Resources.cs:line 207
   at CivOne.Units.BaseUnit.SetIcon(Char page, Int32 col, Int32 row) in E:\proj\CivOneMaster\src\Units\BaseUnit.cs:line 862
   --- End of inner exception stack trace ---
   at System.RuntimeTypeHandle.CreateInstance(RuntimeType type, Boolean publicOnly, Boolean wrapExceptions, Boolean& canBeCached, RuntimeMethodHandleInternal& ctor)
   at System.RuntimeType.CreateInstanceSlow(Boolean publicOnly, Boolean wrapExceptions, Boolean skipCheckThis, Boolean fillCache)
   at System.Activator.CreateInstance(Type type, Boolean nonPublic, Boolean wrapExceptions)
   at CivOne.Reflect.GetTypes[T]()+MoveNext() in E:\proj\CivOneMaster\src\Reflect.cs:line 73
   at System.Linq.OrderedEnumerable`1.TryGetFirst(Func`2 predicate, Boolean& found)
   at System.Linq.Enumerable.TryGetFirst[TSource](IEnumerable`1 source, Func`2 predicate, Boolean& found)
   at CivOne.SaveDataAdapter.GetUnitType(Byte typeId) in E:\proj\CivOneMaster\src\SaveDataAdapter.cs:line 27
   at System.Linq.Enumerable.SelectIPartitionIterator`2.PreallocatingToArray(Int32 count)
   at CivOne.SaveDataAdapter..ctor() in E:\proj\CivOneMaster\src\SaveDataAdapter.cs:line 330
   at CivOne.Common.get_AllowSaveGame() in E:\proj\CivOneMaster\src\Common.cs:line 355
   at CivOne.Screens.GamePlay..ctor() in E:\proj\CivOneMaster\src\Screens\GamePlay.cs:line 413
   at CivOne.Screens.NewGame.HasUpdate(UInt32 gameTick) in E:\proj\CivOneMaster\src\Screens\NewGame.cs:line 238
   at CivOne.RuntimeHandler.Update() in E:\proj\CivOneMaster\src\RuntimeHandler.cs:line 63
   at CivOne.RuntimeHandler.OnUpdate(Object sender, UpdateEventArgs args) in E:\proj\CivOneMaster\src\RuntimeHandler.cs:line 93
   at CivOne.GameWindow.Update(Object sender, EventArgs args) in E:\proj\CivOneMaster\runtime\sdl\src\GameWindow.cs:line 40
   at CivOne.SDL.Window.Run() in E:\proj\CivOneMaster\runtime\sdl\src\SDL\Window.cs:line 96
   at CivOne.Program.Main(String[] args) in E:\proj\CivOneMaster\runtime\sdl\src\Program.cs:line 89