Unable to open Options Page

I have the relevant entry in my manifest file:

  "options_ui": {
    "page": "options/options.html"
  },  

However I’m trying to open it upon click of a floating <div> element, injected in the page by my content script this is the code, the log never fires:

function LoadSetup(){    
    let btn_settings = document.getElementById("settings_link");    
    btn_settings.addEventListener("click", () => {
      console.log('hello');
      //browser.runtime.openOptionsPage();      

      browser.runtime.openOptionsPage()
        .then(onOpened)
        .catch(onError);

      function onOpened() {
        console.log(`Options page opened`);
      }

      function onError(error) {
        console.log(`Error: ${error}`);
      }

      //let opening = browser.runtime.openOptionsPage();
      //opening.then(onOpened, onError);

    });  
}

Found the answer here: