Don't throw on missing member (#1815)

Author: lahma

src/NJsonSchema.CodeGeneration/DefaultTemplateFactory.cs

@@ -400,11 +400,6 @@ public override IMemberAccessor GetAccessor(Type type, string name)
 
                 accessor = baseMemberAccessStrategy.GetAccessor(type, name);
 
-                if (accessor == null)
-                {
-                    throw new InvalidOperationException();
-                }
-
                 return accessor;
             }
         }