Warning: Trying to access array offset on value of type bool in Drupal\opigno_module\Controller\OpignoModuleController->userResult() (line 937 of modules/contrib/opigno_module/src/Controller/OpignoModuleController.php).

I've got this error too

Warning: Trying to access array offset on value of type bool in Drupal\opigno_module\Controller\OpignoModuleController->userResult() (line 937 of modules/contrib/opigno_module/src/Controller/OpignoModuleController.php).

In the module result page after complete a training.

This is because the course has no mandatory_steps

So line 936

$last_mandatory_step = end($mandatory_steps);

return FALSE because $mandatory_steps is empty.

And so the next line (937)

$last_mandatory_step_key = array_search($last_mandatory_step["cid"], $steps_cids_mapping);

generate the warning notice

In the steps described in the issue summary, I think the mention, that none activity has been set as mandatory, has been forgetten.

This should do the trick

Rerolled #5 patch.