invoiceninja/app/Exceptions/PaymentRefundFailed.php

<?php

namespace App\Exceptions;

use Exception;

class PaymentRefundFailed extends Exception
{ 
    /**
    * Report the exception.
    *
    * @return void
    */
   public function report()
   {
       //
   }

   /**
    * Render the exception into an HTTP response.
    *
    * @param  \Illuminate\Http\Request  $request
    * @return \Illuminate\Http\Response
    */
   public function render($request)
   {
       return response()->json([
           'message' => 'Unable to refund the transaction'
       ], 401);
   }
}