mask.rb in graphql-preview-0.0.5

- old
+ new

@@ -1,7 +1,8 @@
 module GraphQLPreview
   class Mask
     def self.call(member, context)
+      return false unless member.respond_to?(:metadata)
       return false unless member.metadata.key?(:preview_toggled_by)
       unless context.key?(:schema_previews)
         raise ArgumentError, "You are using the `GraphQLPreview::Mask`, but key `:schema_previews` was not provided to the `context`"
       end
 