after invoke some times, the `type: ['string', 'object']` --> `type: ['string'].

[jeff0905]

after invoke some times. the type: ['string', 'object'] --> `type: ['string'].

[jeff0905]

  type: ['string', 'object'],
  test: function(cb) {
    const thisField = this.value;
    // check....
    cb();
  }

[jeff0905]

type.js:90 Uncaught TypeError: list.map is not a function
at Fn.types [as test] (type.js:90)
at schema.js:331
at run (iterator.js:5)
at mapSeries (iterator.js:18)
at Schema.validate (schema.js:197)
at iterator (schema.js:314)
at run (iterator.js:5)
at mapSeries (iterator.js:18)
at onValidate (schema.js:251)
at Fn.test (event.js:53)
at schema.js:331
at run (iterator.js:5)
at mapSeries (iterator.js:18)
at Schema.validate (schema.js:197)

[jeff0905]

if i should code like this
email: [
{type: "string", required: true},
function(cb) {
// test if email address (this.value) already exists
// in a database and call this.raise() if it does
cb();
}
]
because this code before:
type: ['string', 'object'],
test: function(cb) {
const thisField = this.value;
// check....
cb();
}

[jeff0905]

after check my code, i found that if we invoke some times , the type: ['string', Number] throw errors,

but, type: ['string', 'number] can't throw error after invoking some times.

[tmpfs]

Thanks for the bug report @jeff0905, can you provide a copy and paste example that reproduces the issue please. If I can reproduce it, I should be able to fix it quickly. Thanks.