Problem with ::save() and ::delete() functions

[ilchimicopazzo]

Hi guys,
I would use Jresearch 3.2.0 on Joomla 3.9.8 in a PHP 7.2 environment.

But I found some troubles due by ::save() and ::delete() funtions. In particular, the messages said that (for example) "Too few arguments to function JResearchAdminModelMember::delete(), 0 passed in [...]/administrator/components/com_jresearch/controllers/staff.php on line 190 and exactly 1 expected".

Thus I tried to follow this suggestion #18 (comment)

It works fine for ::save() in the Staff section, but it does not work for ::delete() function. In this case the error was "Null primary key not allowed.".

Could you check these functions to be compatible with PHP 7.2 and new Joomla installations?

Thank you very much for your effort!