null value in column "id" of relation "messages" violates not-null constraint

Question

When nodejs 14.x/sequelize 6.5.x save a message, it throws an strange error:

Error in saving/braodcasting a new message DatabaseError [SequelizeDatabaseError]: null value in column "id" of relation "messages" violates not-null constraint

Here is the table structure of message:

Here is the instance of message to be saved:

        let msg = Message.build();
        msg.sender_id = req.viewer.id;
        msg.room_id = room_id;
        msg.type = type;
        msg.set("data.msg_body", req.body.data.msg_body);  
        console.log("new message post msg : ", msg);
  
        await msg.save();  //<<== throws error about null id

Since column id can not be null and the id was assigned during msg.save(), what the error is really complaining about and how to fix it?

Here is the model def:

const { DataTypes, Model } = require('sequelize');
const Op = DataTypes.Op;
const db = require("../startup/db");
const Joi = require('joi');

class Message extends Model {};
Message.init({
    
    room_id: {type: DataTypes.STRING,  //[s,t]idfort-token(seller or poster's)]
               allowNull:false,
    },
    sender_id: {type: DataTypes.INTEGER,
                allowNull:false,    
                validate: {
                    isInt:true,
                },
    },
    type:{
        type:DataTypes.STRING,
    },
    receiver_id : {type: DataTypes.INTEGER},
    data: {
        type: DataTypes.JSONB,
        validate: {
            validateJSONData(value) {
                let counter = 0;
                for (key in value) {
                    if (value[key] !== null) {
                        ++counter;
                    }
                };
                if ( counter === 0) {
                    throw new Error('Empty message!');
                };
            }
        }
    },
    createdAt: DataTypes.DATE,
}, {
    sequelize:db,
    modelName: 'message',
    timestamps:true,
    updatedAt: false,
    indexes: [
        {
            fields: ['room_id']
        }, {
            fields: ['sender_id']
        }, {
            fields : ['receiver_id']
        } , {
            fields : ["type"]
        }
    ]
}); 

module.exports.Message = Message;