fatal error in invitations plugin when trying to access a private form

Description

Getting a fatal error when trying to access to a private form.

Distribution Name and Version

debian:bullseye-slim

FusionDirectory Version

1.4-1

Plugin with the defect

Invitations

PHP version used

php7.4

Origin of php packages

apt-cache policy php7.4 php7.4: Installed: 7.4.33-1+deb11u7 Candidate: 7.4.33-1+deb11u7 Version table: *** 7.4.33-1+deb11u7 500 500 http://deb.debian.org/debian-security bullseye-security/main amd64 Packages 100 /var/lib/dpkg/status 7.4.33-1+deb11u5 500 500 http://deb.debian.org/debian bullseye/main amd64 Packages

Steps to Reproduce

0. Create a Public Form and set it in private
1. Create an invitation for this form and send it to your own mail
2. Go to the link received in the mail (e.g. http://test.example.com:81/invitation.php?token=zF1dhkwypFYFfystmwFzeMW6jHCfm9mOqbn3xOWLptXDnT3wqnFQKYSyr)
3. Click on "Click here to login" or "Click here if you can't login"
4. Get redirected on http://test.example.com:81/privateform.php?token=zF1dhkwypFYFfystmwFzeMW6jHCfm9mOqbn3xOWLptXDnT3wqnFQKYSyr and get the error I showed above.

Actual behavior:

I get this error : Erreur Fatale Non attrapé : Error : Call to a member function inputValue() on null

When I refresh the page, I don't have the error any more and the private form ends up being displayed without me having to log in. The same thing happens wether I click on "Click here to login" or "Click here if you can't login".

Expected behavior:

The form is private so when I click on "Click here to login" it should actually ask me to login and the option "Click here if you can't login" should not be displayed, or at least shouldn't let me access the form.

Additional Information

I don't know if it's relevant but here's my apache config :

cat /etc/apache2/sites-available/000-default.conf
Listen 81

<VirtualHost *:81>
    ServerAdmin admin@test.example.com
    ServerName test.example.com
    DocumentRoot /usr/share/fusiondirectory/html
    <Directory /usr/share/fusiondirectory/html>
        Options FollowSymLinks
        AllowOverride All
        Require all granted
    </Directory>
    ErrorLog ${APACHE_LOG_DIR}/fusiondirectory_error.log
    CustomLog ${APACHE_LOG_DIR}/fusiondirectory_access.log combined
</VirtualHost>

It's my first time creating an issue here, let me know if you need more information.