title: Formik's handleChange throws "TypeError: null is not an object (evaluating '_a.type')" on DateInput's onChange
body: <p>When I just add the handleChange from Formik to the "semantic-ui-calendar-react" DateInput component I get the following error on selection a date.</p>
  
  <p><a href="https://imgur.com/a/BOEDEXc" rel="nofollow noreferrer">https://imgur.com/a/BOEDEXc</a> "console output"</p>
  
  <p>AddWishlistFormDate.tsx</p>
  
  <pre><code> import { FormikErrors, FormikProps, withFormik } from 'formik';
   import * as React from 'react';
   import { DateInput } from 'semantic-ui-calendar-react';
   import { Button, Form } from 'semantic-ui-react';
  
   export interface FormValues {
    date: string;
  }
  
   interface Props {
    submit: (values: FormValues) =&gt; Promise&lt;FormikErrors&lt;FormValues&gt; | null&gt;;
  }
  
   class C extends React.PureComponent&lt;FormikProps&lt;FormValues&gt; &amp; Props&gt; {
    public render() {
      const {
        values: { date },
        handleChange,
        handleSubmit,
      } = this.props;
      return (
        &lt;Form onSubmit={handleSubmit}&gt;
          &lt;Form.Field&gt;
            &lt;label&gt;Date&lt;/label&gt;
            &lt;DateInput
              name="date"
              value={date}
              iconPosition="left"
              onChange={handleChange}
            /&gt;
          &lt;/Form.Field&gt;
          &lt;Button type="submit"&gt;Add&lt;/Button&gt;
        &lt;/Form&gt;
      );
    }
  }
  
   export const AddWishlistFormDate = withFormik&lt;Props, FormValues&gt;({
    mapPropsToValues: () =&gt; ({ date: '' }),
    handleSubmit: async (values, { props, setErrors }) =&gt; {
      const errors = await props.submit(values);
      if (errors) {
        setErrors(errors);
      }
    },
  })(C);
  </code></pre>
  
  <p>run it with following</p>
  
  <pre><code> const handleSubmit = async (values: FormValues) =&gt; {
      console.log(values);
      return null;
    };
    return &lt;AddWishlistFormDate submit={handleSubmit} /&gt;;
  </code></pre>