With `Formik`, my input shows an `[object Object]` value instead of behaving in a standard manner.

[Code is here](https://codesandbox.io/s/formik-v3-cbk8g).

```
import React from "react";
import ReactDOM from "react-dom";
import { Formik, Field, Form, ErrorMessage } from "formik";
import * as Yup from "yup";
import "./styles.css";

const SignupForm = () => {
  return (
    <Formik
      initialValues={{ email: "" }}
      validationSchema={Yup.object({
        email: Yup.string()
          .email("Mauvais e-mail")
          .required("Champ requis")
      })}
      onSubmit={values => {
        alert(JSON.stringify(values, null, 2));
      }}
    >
      <Form>
        <label htmlFor="email">Email</label>
        <ErrorMessage name="email" />
        <br />
        <Field name="email" type="email" />
        <button type="submit">OK</button>
      </Form>
    </Formik>
  );
};

ReactDOM.render(<SignupForm />, document.querySelector("#root"));

```