I can’t find the exact ticket, but maybe 2 years back a different approach to showing error messages was introduced. In production environment, most of the messages were hidden for the application user and shown only in the log. If you set the environment to development, they show also in the application. Since HTML Architect runs as an app, the environment should be set to development, so you see all the errors.
Of course any finetuning of what is shown and how makes sense for working with the Architect as compared to the app user experience.