Property 'username' has no initializer and is not definitely assigned in the constructor string code example

Example 1: Property 'firstName' has no initializer and is not definitely assigned in the constructor

"angularCompilerOptions": {
    //   ...
    "strictPropertyInitialization": false
    //   ...
  }

Example 2: Property 'form' has no initializer and is not definitely assigned in the constructor.

"strictPropertyInitialization": false