[FIX] web_editor: fix some 'unused variable' linter errors

Commit [1] introduced at least 2 linter errors, which this commit is
fixing.

[1]: https://github.com/odoo/odoo/commit/6df67a28c2f113572acd4a3db19ab6b1bd37e7da

Part of https://github.com/odoo/odoo/pull/54311