Fixed passing null for number_format is deprecated for downloadable p…

…roducts (OpenMage#3382)

Co-authored-by: Ng Kiat Siong <kiatsiong.ng@gmail.com>
Co-authored-by: kyrena <78410399+kyrena@users.noreply.github.com>

app/code/core/Mage/Downloadable/Block/Adminhtml/Catalog/Product/Edit/Tab/Downloadable/Links.php

@@ -227,7 +227,7 @@ public function getLinkData()
      */
     public function getPriceValue($value)
     {
-        return number_format($value, 2, null, '');
+        return number_format($value ?? 0, 2, null, '');
     }
 
     /**