checkdate error, int expected string provided

I would like so see something more than a cast here. That form element was inherited from Drupal 7 and not updated for Drupal 8+, and the way it is handling dates is not what we do in Drupal these days.

For example, a default value of an array, and parsing the string with strtotime(), which isn't necessary because the front-end date picker delivers a fixed format. So the description of what to enter is wrong too.

I would like to update these '#type' => 'date' form elements, and add a test case to make sure that values can be entered in this form and submitted without an error. There is a test case that will be put in as part of #3476179: Route "regcode.admin_list" does not exist which just verifies that the form page can be accessed, but that should be modified to fill out the form and submit it as well. For all the tabs.

Can you work on this?

As far as the test, what I had in mind is to modify RegcodeSettingsTest to add a new test case which does drupalGet('admin/config/people/regcode/settings') then sets values for all the fields, then does submitForm(). Nothing more than that - that would have been enough to detect this issue that you reported because the test would have failed with the error you reported.

Also I found yet another flaw that since then appears to have been fixed already: both regcode_create_number and regcode_create_case need to be typecasted as integer and boolean for the code to work.

Yes, I did some general work trying to fix typing problems. I would really like to get these form settings into configuration, so that the entered values can be remembered and used as the defaults - I find it annoying that every time I go to this form I have to enter all the values and make all the selections over again because it doesn't remember my previous entries.

I think the only outstanding issues I wanted to get in before the next release are #3476179: Route "regcode.admin_list" does not exist and #3227669: Display all users which used the current regcode., in addition to this current issue.

Very nice. Thank you! Merged.