`tutor ... do settheme default` is meant to revert to the
default theme. However, in its current implementation, it
creates SiteTheme objects pointing to a theme named "default",
which doesn't exist, resulting in errors like:
Theme dirs:
[Path('/openedx/themes')]]
Traceback (most recent call last):
File "/openedx/edx-platform/openedx/core/djangoapps/theming/helpers.py", line 204, in get_current_theme
themes_base_dir=get_theme_base_dir(site_theme.theme_dir_name),
File "/openedx/edx-platform/openedx/core/djangoapps/theming/helpers.py", line 242, in get_theme_base_dir
raise ValueError(
ValueError: Theme 'default' not found in any of the following themes dirs,
This works from the perspective of the user, because a missing theme is
treated as the default theme. However, the errors are unneccesary &
confusing.
By simply deleting & not recreating SiteTheme objects instead,
we are able to revert to the default theme while keeping the
logs clear of theming errors.
