Non standard and unserialisable data structure returned from nested schemas

[eliothowes]

See https://runkit.com/eliothowes1090/hannibal-error-example for example of issue.

Given the following schema:

{
    type: 'object',
    schema: {
        foo: {
            type: 'array',
            validators: {
                max: 2
            },
            schema: {
                type: 'string',
                validators: {
                    enum: [
                        'fish', 
                        'chips'
                    ]
                }
            }
        }
    }
}

And the following data structure:

{
    foo: [
      '',
      'not fish',
      'not chips'
    ]
}

The following error object is returned:

foo: [
  {enum: "string:  is not one of: fish, chips"},
  {enum: "string: not chips is not one of: fish, chips"},
  {enum: "string: not chips is not one of: fish, chips"},
  max: "array is too long, requires: 2 items and was: 3"
]