lack of parity in custom element behaviour

[o-t-w]

You can see my Svelte component working correctly here: https://codesandbox.io/s/weathered-platform-x58lq

When I turn it into a custom element, most of the behaviour continues to work, but I can no longer share images:
This is the src code: https://github.com/o-t-w/share-web-component/blob/master/src/index.svelte
This is the custom element failing to work: https://codepen.io/cssgrid/pen/WNNyRyz?editors=1010 - If you test the component in Chrome on Android (currently the only browser that supports web share API for images) you'll see that the shareimg prop isn't doing anything

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[stale]

This issue has been closed as it was previously marked as stale and saw no subsequent activity.