TypeError: personalization.toJSON is not a function

[frzkhan]

Im using the following config to send email verification in loopback, which results in this error
works fine with previous version
Not working on ^2.2.4
Working on ^2.1.3

const options = {
      type: 'email',
      to: 'test@local.email,
      from: 'test@local.email',
      subject: 'subject',
      text: '-',
      html: '-',
      sendGridConfig: {
        personalizations: [{
          to: [{ email: 'test@local.email' }],
          substitutions: {
            '-test-': 'test',
          },
        }],
        templateId: 'sendgridtemplateId'
      }
    }