The feature detection for event listener third argument is calling the wrong method on `window` ```js window.remove('testpassive', arg, arg); ``` It should be ```js window.removeEventListener('testpassive', arg, arg); ``` This comes from the URL referenced in the comment above it: https://github.com/WICG/EventListenerOptions/blob/gh-pages/explainer.md#feature-detection https://github.com/jonasgeiler/svelte-tiny-virtual-list/blob/f179308e3262386b42237fc002d76093a58df5e4/src/lib/VirtualList.svelte#L20