Copy Page action fails on browsers without ClipboardItem

[schickling]

Summary

When using the copy action in Firefox (and other browsers that do not expose window.ClipboardItem), clicking Copy page throws a runtime error and nothing is written to the clipboard.

Steps to reproduce

1. Install starlight-contextual-menu@0.1.3 in a Starlight site.
2. Open the site in Firefox 130 (or Safari 18).
3. Click the Copy page button.

Expected behaviour

The page markdown should be copied to the clipboard.

Actual behaviour

The browser console shows:

Failed to copy Markdown: ReferenceError: ClipboardItem is not defined
    at Object.action (contextual-menu.js:18:31)

Context

The injected script creates a new ClipboardItem(...) without checking whether the API exists. Firefox only supports navigator.clipboard.writeText, so the constructor reference throws. A small feature-detection guard (falling back to writeText) would fix the issue.

Suggested fix

Guard the Copy Page handler with:

if (typeof window.ClipboardItem === "undefined") {
  await navigator.clipboard.writeText(markdown)
  return
}

Happy to help test a patch—thanks!

[schickling]

Opened #14 with a fix that falls back to navigator.clipboard.writeText when ClipboardItem is missing.

[reynaldichernando]

hi @schickling , thanks for opening the issue and making PR for it
for some reason i don't get notifications for it, which is why i missed it, checking it now and i'll get back ASAP