[Django Instrumentation] Exception on settings not raised when using instrumentor and django environ

Describe your environment Describe any aspect of your environment relevant to the problem, including your Python version, platform, version numbers of installed dependencies, information about your cloud hosting provider, etc. If you're reporting a problem with a specific version of a library in this repo, please check whether the problem has been fixed on main.

Using python 3.8, Django 4.1.9 and django-environ 0.10.0 on a docker python:3.8-slim-buster

Steps to reproduce
Describe exactly how to reproduce the error. Include a code sample if applicable.

• Install a django project and use django environ for settings.
• Declare a settings based on an env variable not existing (on settings.py) with no default:
  NOT_EXISTING = env.str("NOT_EXISTING")

What is the expected behavior?
What did you expect to see?

See the exception in the console: django.core.exceptions.ImproperlyConfigured: Set the NOT_EXISTING environment variable

What is the actual behavior?
What did you see instead?

No error. And Django settings not loaded and backed up to the default ones.

Additional context
Add any other context about the problem here.

Reproduce the issue with a Django project's settings.py using django-environ and a missing NOT_EXISTING variable, then inspect the Django instrumentor's settings-loading entry point. Done means Django raises django.core.exceptions.ImproperlyConfigured instead of falling back to default settings; no test file is named in the issue.