property 'firstname' has no initializer and is not definitely assigned in the constructor code example

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

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

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

//inside tsconfig.json file
"angularCompilerOptions": {
    //   ...
    "strictPropertyInitialization": false
    //   ...
  }