Module development and code questions

I have tried to move to the brand new GitLab CI for testing, following the guidelines on this documentation page.
Basically I've added a .gitlab-ci.yml, which is an exact copy of Drupal Association's template.gitlab-ci.yml (as renommended on that page). And, indeed, doing so automatically triggers a test pipeline. So far, so good.

Hello, 

After upgrading to Drupal 10 i got an Error in the following function:

Can you please help me ? 

public function saveappointmentuser(){

        @$user_current = \Drupal::currentUser()->id();
        @$user_info_current = \Drupal\user\Entity\User::load(\Drupal::currentUser()->id());
        $userID_current = $user_info_current->uid->value;

I have created a custom edit form into which I want to load database field values as form field default values. 

Hello,

I want to switch node's form mode by a toggle button (boolean field).

Here is my code:

I'm getting to grips with custom code in D10 after several years of simple development in D7.

What code should you use in the Form Submit function shown below?  (In D7 I think it was $form_state['redirect']='pets'; to send the user to the pets Views listing.

Hello,

I developped a module having as goal to to let's say the basic CRUD operations.

For instance the GET (corresponding to read) is OK, POST (create) is OK and now, for DELETE, I'm face to an error that I've analysed but no reason found yet.

Details about my rest api implementation:

This is my uri_path: