Enabling dark-mode shows warning and doesn't work

[hgluka]

Describe the bug

Enabling dark-mode shows the following warning/error:

<WARN> [18:03:03] Warning: JavaScript error: GError: Domain: "WebKitJavascriptError", Code: 699, Message: nyxt:new:1: SyntaxError: Unexpected identifier 'e'. Expected ')' to end an argument list.
<INFO> [18:03:03] Dark mode enabled.

But dark mode is not actually enabled.
The same warning is shown when running the darken bookmarklet command directly.

Precise recipe to reproduce the issue

1. Open any webpage in Nyxt.
2. Enable dark-mode.
3. Read the message buffer.

or

1. Open any webpage in Nyxt.
2. Enable bookmarklets-mode.
3. Execute the darken command.
4. Read the message buffer.