make person_id and company_id optional on job

models/job.php

@@ -3,16 +3,18 @@ include_once __DIR__ . '/../database/db.php';
 
 class Job {
     public $id;
-    public $person_id;
     public $job_type;
-    public $company_id;
     public function __construct($id, $person_id, $job_type, $company_id) {
         $this->id = $id;
+        if($person_id){
             $this->person_id = $person_id;
+        }
         $this->job_type = $job_type;
+        if($company_id){
             $this->company_id = $company_id;
         }
     }
+}
 
 class Jobs {
     static function find(){