Error "Property has no initializer" in TypeScript: how to fix?

Hello everyone! I'm a beginner in TypeScript and Angular, and I've encountered a very strange error. I have a component where I declare a property, but TypeScript complains that it is not initialized. Here is my code: ```typescript import { Component, Input } from '@angular/core'; @Component({ selector: 'app-user', template: ` ` }) export class UserComponent { @Input() user: User; public userName: string; private id: number; constructor() { // Do nothing in the constructor } ngOnInit() { this.userName = this.user.name; this.id = this.user.id; } } ``` When compiling, I get errors: - `Property 'user' has no initializer and is not definitely assigned in the constructor.` - `Property 'userName' has no initializer and is not definitely assigned in the constructor.` - `Property 'id' has no initializer and is not definitely assigned in the constructor.` How can I fix this? I thought that if I use `@Input()`, the property will be initialized from the parent component. And `userName` and `id` are initialized in `ngOnInit()`. Why does TypeScript require initialization in the constructor? What is the correct way to handle this?