It can be reproduced here:
https://alvarotrigo.com/fullPage/examples/methods.html#content

Steps:

1. Go to Section 2
2. Click on destroy('all')
3. Click on undestroy() to init fullPage.js again

Notice the error int he console:

Referring to this line:

It can also be reproduced in this codepen with version 4.0.35:
https://codepen.io/alvarotrigo/pen/jEPExbd

1. Scroll to section 2
2. Click destroy
3. Click init