[matthewsong18]

Problem

Opening popup.html directly from the address bar, a bookmark, or the
Firefox homepage ran the same code as clicking the extension icon.
WebToEpub opened a second tab and used the first WebToEpub tab as the
source page.

Firefox lets WebToEpub read its own moz-extension:// URL, so the
existing URL check doesn't stop it and let it attempt injection. Firefox blocks content
scripts on extension pages and returned Missing host permission for the tab.

Fix

• Use tabs.getCurrent() when the URL has no query string. If WebToEpub
  is already open in a browser tab, initialize the interface there.
• Only try to load a source page when the URL contains a valid id
  parameter. A direct link without an ID opens the interface without
  importing a page.

Refactor

• Renamed isRunningInTabMode() to isOpenInBrowserTab() to make it
  clear that the check is about where WebToEpub is open.
• Renamed configureForTabMode() to importPageFromTabIdInUrl() to
  describe what it does and where it gets the source tab ID.

Testing

• Reproduced the error in Firefox by opening popup.html directly.
• To verify in Firefox, open bare popup.html and check that the
  interface loads in one tab without an error.

Refer to #3148

[gamebeaker]

@matthewsong18 can you merge it yourself?

[matthewsong18]

@matthewsong18 can you merge it yourself?

@gamebeaker Sorry, I'm not sure what you mean? Do you mean merge the PR into the main branch? Or merge updates from main into here? I don't have permission to merge if you mean the first.