Uncaught TypeError: Cannot read properties of undefined (reading 'length')

[bethanyfish]

I'm getting this error only on one instance.

Working: https://0rnpvmpswe06x9m3-27895142.shopifypreview.com/account/register AND https://0rnpvmpswe06x9m3-27895142.shopifypreview.com/account/login

Not working: https://0rnpvmpswe06x9m3-27895142.shopifypreview.com -- hover over 'Account'

My code:

// Custom form validation for account and registration forms using Vanilla Validator
var registerConfig = {
  container: '#create_customer',
  validationBy: 'onclick',
  validateOnFieldChanges: true,
  selectors: {
    required: 'vv-required'
  },
  messages: { // can also be set by html attribute 'data-message-error'
    required: 'This field is required'
  }
};
var registerValidator = new VanillaValidator(registerConfig);

var loginConfig = {
  container: '#customer_login',
  validationBy: 'onclick',
  validateOnFieldChanges: true,
  selectors: {
    required: 'vv-required'
  },
  messages: { // can also be set by html attribute 'data-message-error'
    required: 'This field is required'
  }
};
var loginValidator = new VanillaValidator(loginConfig);

The login link provided is essentially the same form as the mini login form. Why does one work and not the other?

ERROR: