Trying to access array offset on value of type null in Drupal\opigno_h5p\TypeProcessors\FillInProcessor->generateHTML()

Problem/Motivation

Warning appears when seen the results using a Documention Tool widget from H5P

Steps to reproduce

Create a course with a Documentation Tool widget activity, use Standard Page as Page type and Text input field editor element as Library.
Go through the activity and see the result page to get the warning.

Proposed resolution

The code works with the $crp array parameter before checking if it's set, that it does just after. So just move that line of code.