Fix unserialize error on php 8.1

CRM/Zapier/Form/ZapHooks.php

@@ -24,7 +24,7 @@ class CRM_Zapier_Form_ZapHooks extends CRM_Core_Form {
       ]
     ]);
 
-    $zapHooks = unserialize(Civi::settings()->get('zapierHooks'));
+    $zapHooks = unserialize(Civi::settings()->get('zapierHooks') ?? '') ?: [];
     $this->setDefaults($zapHooks);
 
     // export form elements

CRM/Zapier/Utils.php

@@ -55,7 +55,7 @@ class CRM_Zapier_Utils {
   }
 
   public static function getZapHooks() {
-    return self::unserialize_recursive(Civi::settings()->get('zapierHooks'));
+    return self::unserialize_recursive(Civi::settings()->get('zapierHooks') ?? '') ?: [];
   }
 
   public static function getZapHook($name) {