Formik is dirty when field undefined and not null

[StudioSpindle]

❓Question

I am using a fetch to populate the initial values for Formik. One of the fields is null in the fetch result (password).

When I use this in a field, and change the input field to a value, the dirty state of the form becomes true.

Then when I remove that value again Formik will stay 'dirty'. Since Formik makes the field 'undefined' and not 'null'.

Does someone have a workaround for this?

[StudioSpindle]

Example: https://codesandbox.io/s/strange-cerf-29xw6

Steps to reproduce:

• Fill in the second input field with a word. Note that the submit button becomes active.
• Remove that entire word again from that field.

Outcome: The submit button stays clickable.
Expected outcome: The submit button should become disabled again.