Use an explicit cast instead of "as" since there should always be a namespace.

src/Generator/Generators/CSharp/CSharpTextTemplate.cs

@@ -1277,14 +1277,12 @@ namespace CppSharp.Generators.CSharp
 
             var method = function as Method;
 
-            bool isValueType = false;
-            bool needsInstance = false;
+            var isValueType = false;
+            var needsInstance = false;
 
             if (method != null)
             {
-                var @class = method.Namespace as Class;
-
-                if (@class != null)
+                var @class = (Class) method.Namespace;
                 isValueType = @class.IsValueType;
 
                 needsInstance = !method.IsStatic;