Add missing `Variable.Type` null check. (#1430)

Work around an unhandled case of the type of a variable

src/AST/ASTVisitor.cs

@@ -470,6 +470,11 @@ namespace CppSharp.AST
             if (!VisitDeclaration(variable))
                 return false;
 
+            // TODO: Remove this null check once CppParser can properly handle auto types.
+            // This is workaround for https://github.com/mono/CppSharp/issues/1412.            
+            if (variable.Type == null)
+                return false;
+
             return variable.Type.Visit(this, variable.QualifiedType.Qualifiers);
         }
 

tests/CSharp/CSharp.h

@@ -1429,4 +1429,16 @@ namespace CXXRecordDeclWithoutDefinition
 
     template <> struct it<list<>> { };
     template <> struct it<list<> const> { };
-}
+}
+
+template<int... n>
+struct TestVariableWithoutType
+{
+    template<typename... Args>
+    static constexpr int create(Args... args)
+    {
+        return {};
+    }
+
+    static constexpr auto variable = create(n...);
+};