Call to a member function id() on null in line 24 of modules/contrib/flag_lists/src/Access/FlaggingCollectionAccessControlHandler.php

Problem/Motivation

I updated my Drupal to 9.3.6 from 9.1.8. In that process I updated the Flag and Flag Lists.

My previous version of Flag List was 4.0.0.-rc1. After the update, it's now Flag 4.0.0-rc2

Steps to reproduce

When you go to home page and click on the My flagging Collection main menu (/flagging_collection), it shows following error:

The website encountered an unexpected error. Please try again later.
Error: Call to a member function id() on null in Drupal\flag_lists\Access\FlaggingCollectionAccessControlHandler->checkAccess() (line 24 of modules/contrib/flag_lists/src/Access/FlaggingCollectionAccessControlHandler.php).

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes