Accept enum undefined

[minettiandrea]

No description provided.

[tdegrunt]

Hi there,

Thanks for contributing and sorry for the late answer.

Can you explain why this is needed? The standard says the following:

enum: The value of this keyword MUST be an array.
http://json-schema.org/latest/json-schema-validation.html#rfc.section.6.23

This change would be in contradiction with this, but maybe I'm missing out on a certain use case?

Thank you,
Tom

[awwright]

The test that @minettiandrea provided might have an insight, it looks like the "enum" keyword might incorrectly fail validation if it's set to null/undefined, as opposed to not existing.