How to Config babel.config to extend classes

[Sudarshan-Jagadale]

I am building a react-component.
I am using some Es6 class like
class MyClass extends MainClass { // ... } let instance = new MyClass()
Code is complied successfully
but when i run it.
It throws an error Uncaught TypeError: Class constructor MainClass cannot be invoked without 'new'
I am using "webpack": "4.43.0", "npm": "4.43.0", node:14.4.0 and nwb : 0.25.2.