Fix strange build issue

BepInEx.Core/Console/Windows/Kon.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Runtime.InteropServices;
 
 #if NET35
@@ -103,7 +103,7 @@ namespace BepInEx.ConsoleUtil
             if (!flag)
                 return;
             var num = bufferInfo.wAttributes;
-            num &= isBackground ? -241 : -16;
+            num &= isBackground ? (short)-241 : (short)-16;
             num = (short) ((ushort) num | (ushort) color);
             SetConsoleTextAttribute(conOut, num);
         }