Indicate in the UI when an API is not supported

[simevidas]

Instead of just throwing an error in the browser’s console, consider showing in the site’s UI that an error occurred; e.g. when the user clicks on a button which causes an error, you could add

<span style="color: red;">⚠</span>

to the button:

---

Update: Using a pseudo-element would probably be a better idea.

button.error::after {
    content: " ⚠";
    color: red;
}