Node.js Sequelize : ReferenceError: model is not defined, when using Through association

I need to create a many to many association in sequelize.

I am having this error :

ReferenceError: alertSMSRule is not defined

Here is the code concerning the error :

file alertSMSrule.model.js :

module.exports = (sequelize, Sequelize) => {
    const AlertSMSRule = sequelize.define("alertSMSRule", {
      name: {
        type: Sequelize.STRING
      },
      number: {
        type: Sequelize.STRING
      }
    });
  
    return AlertSMSRule;
  };

file phoneNumber.model.js :

module.exports = (sequelize, Sequelize) => {
    const PhoneNumber = sequelize.define("phoneNumber", {
      name: {
        type: Sequelize.STRING
      },
      number: {
        type: Sequelize.STRING
      }
    });
  
    return PhoneNumber;
  };

file index.js :

db.phoneNumber = require("./phoneNumber.model.js")(sequelize, Sequelize);
db.alertSMSRule = require("./alertSMSRule.model.js")(sequelize, Sequelize);

// line below is giving the error
alertSMSRule.belongsToMany(phoneNumber, { through: 'SMSRule_PhoneNumbers' });
phoneNumber.belongsToMany(alertSMSRule, { through: 'SMSRule_PhoneNumbers' });

Sequelize is properly imported and initialized. I have a bunch of other models associations working very well, but they are all hasMany / belongsTo. This is my first belongsToMany association and it's the only one with error.

Did i miss something about creating a many to many association with sequelize ? I have checked sequelize doc and forums and everything is telling me this should work this way. Source : https://sequelize.org/docs/v6/advanced-association-concepts/advanced-many-to-many/

I found out what is the problem. As we can read on some forums, it's a Javascript error, nothing related to Node.js or Sequelize.

I replaced the code :

alertSMSRule.belongsToMany(phoneNumber, { through: 'SMSRule_PhoneNumbers' });
phoneNumber.belongsToMany(alertSMSRule, { through: 'SMSRule_PhoneNumbers' });

by :

db.alertSMSRule.belongsToMany(phoneNumber, { through: 'SMSRule_PhoneNumbers' });
db.phoneNumber.belongsToMany(alertSMSRule, { through: 'SMSRule_PhoneNumbers' });