MDL-58058 competency: replace other sortorder usages

competency/classes/api.php

@@ -165,7 +165,7 @@ class api {
         require_capability('moodle/competency:competencymanage', $competency->get_context());
 
         // Reset the sortorder, use reorder instead.
-        $competency->set('sortorder', null);
+        $competency->set('sortorder', 0);
         $competency->create();
 
         \core\event\competency_created::create_from_competency($competency)->trigger();

competency/classes/template_competency.php

@@ -53,7 +53,7 @@ class template_competency extends persistent {
             ),
             'sortorder' => array(
                 'type' => PARAM_INT,
-                'default' => null,
+                'default' => 0,
             ),
         );
     }

competency/classes/user_competency_plan.php

@@ -66,7 +66,7 @@ class user_competency_plan extends persistent {
             ),
             'sortorder' => array(
                 'type' => PARAM_INT,
-                'default' => null,
+                'default' => 0,
             ),
         );
     }