set invoice id nullable in error logs

src/db/migrations/20240711115635-create-error-log.js

@@ -10,7 +10,7 @@ module.exports = {
         type: Sequelize.INTEGER
       },
       invoice_id: {
-        allowNull: false,
+        allowNull: true,
         type: Sequelize.INTEGER,
         references: {
           model: 'invoices', 
@@ -37,4 +37,4 @@ module.exports = {
   async down(queryInterface, Sequelize) {
     await queryInterface.dropTable('error_log');
   }
-};
+};