react-styleguidist-build-error

{ [Error: Validation Error

UglifyJs Plugin Invalid Options

options.parallel should be boolean
options.parallel should be integer
options.parallel should match exactly one schema in oneOf
]
  err: 
   [ { keyword: 'type',
       dataPath: '.parallel',
       schemaPath: '#/properties/parallel/oneOf/0/type',
       params: [Object],
       message: 'should be boolean' },
     { keyword: 'type',
       dataPath: '.parallel',
       schemaPath: '#/properties/parallel/oneOf/1/type',
       params: [Object],
       message: 'should be integer' },
     { keyword: 'oneOf',
       dataPath: '.parallel',
       schemaPath: '#/properties/parallel/oneOf',
       params: {},
       message: 'should match exactly one schema in oneOf' } ] }