Issue:

An error occurred when `env._t` was invoked as a function within the `openXbusMessage` method:
TypeError: env._t is not a function at openXbusMessage (debug_manager_xbus.js:33).

Fix:

Replaced the usage of `env._t` with the imported `_t` utility from `@web/core/l10n/translation`.

Fix message body encoding and display.

The worst is that the table is meant to be used by xbus-odoo that can write to it in SQL, so the computed field would not be run.

Migrations script to add the columns would have been missing too.