"format": "idn-email" allows empty string

[davidimagitech]

I came across the following validation error for an empty string value after updating a field's format from email to idn-email:

"JSON is valid against more than one schema from 'oneOf'. Valid schema indexes: 0, 1."

Schema:
{ "properties": { "email": { "oneOf": [{ "format": "idn-email" }, { "const": "" } ] } }, "required": ["email"] }

Test input:
{ "email": "" }

...which means that "format": "idn-email" is accepting an empty string as an email address

[davidimagitech]

On further checking, it appears as if "format": "idn-email" accepts any string, including empty string, on https://www.jsonschemavalidator.net/

[JamesNK]

Unfortunately the idn-email format isn't supported.