erreur fichier provider.classs.php

[DAMIGON]

Dear GLPi user.

For bug reports, you can open. an issue here, provide us :

• The version of the plugin : 1.8.2
• The version of your GLPI : 9.5.6
• The steps to reproduce your issue : clic on "Assistance - Ticket" => error on the page => nothing print
  GLPI log errors :
  👍 [2021-10-18 09:05:35] glpiphplog.CRITICAL: *** Uncaught Exception TypeError: Argument 1 passed to Glpi\Dashboard\Provider::formatMonthyearDates() must be of the type string, null given, called in /var/www/glpi/inc/dashboard/provider.class.php on line 661 in /var/www/glpi/inc/dashboard/provider.class.php at line 1269
  Backtrace :
  inc/dashboard/provider.class.php:661 Glpi\Dashboard\Provider::formatMonthyearDates()
  : Glpi\Dashboard\Provider::ticketsOpened()
  inc/dashboard/grid.class.php:1002 call_user_func_array()
  ajax/dashboard.php:122 Glpi\Dashboard\Grid->getCardHtml()

[DAMIGON]

analyse error