Making NPS survey feedback a required field

We would like to make the feedback field of the NPS Survey required so that each time we request an NPS score, they have to submit some type of text in the feedback area with their score.

We have numbers of responses, but very few actually leave contextual feedback which prevents us from acting on that feedback and making improvements to the customer experience. By implementing this (hopefully) small and easy fix, we can start to gain more context around our NPS score.