CRM/Activityprofile/APIWrappers/Profile: unset group_id if empty, otherwise API error.

CRM/Activityprofile/APIWrappers/Profile.php

@@ -28,6 +28,11 @@ class CRM_Activityprofile_APIWrappers_Profile {
       }
     }
 
+    // Fields such as group_id will fail if empty
+    if (isset($apiRequest['params']['group_id']) && empty($apiRequest['params']['group_id'])) {
+      unset($apiRequest['params']['group_id']);
+    }
+
     // This is a profile with activity fields, but without an activity_id
     // Let's create a new contact and a new activity.
     // We only do the minimum and let profile.submit do the rest.