TypeError: cannot set properties of null (setting 'innerHtml')

I have created a simple angular service that initializes the inner html of a div tag in the main component of my angular project and is called in multiple components. When I run my tests I get the above karma error. I assume this is because the component is not created in the service.spec.ts file. I have checked and the class is defined in the main html file.

service.ts function:

onCLick(value: string): void {
   document.querySelector('div.class').innerHtml = value;
}

service.spec.ts:

descirbe('ClickedService', () => {
   let service: ClickedService;

   beforeEach(() => {
      TestBed.configureTestingModule({});
      service = TestBed.inject(ClickedService);
   });

   to("#onClick should add to innerHtml", () => {
       service.onClick('test value'); // error is here
   });
});