Fix mapper 245 via an assert instead

BizHawk.Emulation.Cores/Consoles/Nintendo/NES/Boards/MMC3_family/Mapper245.cs

@@ -14,6 +14,7 @@ namespace BizHawk.Emulation.Cores.Nintendo.NES
 			switch (Cart.board_type)
 			{
 				case "MAPPER245":
+					AssertVram(8);
 					break;
 				default:
 					return false;
@@ -74,14 +75,7 @@ namespace BizHawk.Emulation.Cores.Nintendo.NES
 				}
 				else
 				{
-					if (VRAM != null) // Bad dumps such as Chu Han Zheng Ba - The War Between Chu & Han (Ch) [b1] can get us into this situation without VRAM
-					{
-						return VRAM[addr];
-					}
-					else
-					{
-						return 0xFF;
-					}
+					return VRAM[addr];
 				}
 			}
 			else