Property 'active' has no initializer and is not definitely assigned in the constructor.ts(2564)
//inside tsconfig.json file
"angularCompilerOptions": {
    //   ...
    "strictPropertyInitialization": false
    //   ...
  }
  
  Just go to tsconfig.json and set
"strictPropertyInitialization": false
to get rid of the compilation error.
Otherwise you need to initialize all your variables which is a little bit annoying
