[FIX] web_editor: ensure a crash during save does not lock the editor

An error has been introduced by [1]. Indeed `response.data` does not
exist, but `response.message.data` does. However, the whole `if` clause
there seems now useless so this commit removes it. The whole file is
being refactored anyway with the new editor.

[1]: https://github.com/odoo/odoo/commit/ab4000fb3cf8fa54ba714ceceec391b78d73755e#diff-b1b550326b2d36a24e94e52c3901d1fbL513



closes odoo/odoo#52534

Signed-off-by: Quentin Smetz (qsm) <qsm@odoo.com>