Bug report: SAML Source Stack Trace For "duplicate key value violates unique constraint"

[4d62]

Describe the bug
A clear and concise description of what the bug is.

To Reproduce
Steps to reproduce the behavior:

1. Navigate to the admin Interface
2. Go to Directory -> Federation and Social login and create a new SAML source
3. Set User matching mode to the second option, the SSO URL to https://company.cloudflareaccess.com/cdn-cgi/access/sso/saml/<unique string>, set the Issuer to https://company.cloudflareaccess.com/<unique id>, leave the rest of the values as default.
4. Expand the "Flow settings" section and set all 3 to existing flows. The default "Pre authentication", the "Welcome to authentik!", and an enrollment flow created with the Cooptonian tutorial.
5. Log out and attempt to log back in

NB:

• The user has a password (set by default admin)
• The user has a webauthn key set
• The account is already connected under https://authentik.company/if/user/#/settings;%7B%22page%22%3A%22page-sources%22%7D (It worked before)
• Before selecting all flows in step 4, the ACS url returned a bad request with the message "Configured flow doesn't exist" (Suddenly) <- When setting "Authentication flow" to "----"
• Issue didn't happen when using a OpenID source instead of SAML
• When setting the Authentication Flow to the other "Welcome to authentik!", it performs as expected and redirects the user back to the login page. Isn't an issue with the source.
• Setting "User matching mode" to the first option resolves the issue

Expected behavior
A "pretty error" appears instead of a stack trace.

Screenshots
If applicable, add screenshots to help explain your problem.

Logs
Log context:

{"http_request": {"args": {}, "method": "GET", "path": "/api/v3/flows/executor/id-sdko-authentication-src/", "request_id": "56c56d01e5a64dcdbb3855650bf77986", "user_agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36"}, "message": "Traceback (most recent call last):\n  File \"/authentik/flows/views/executor.py\", line 287, in get\n    stage_response = self.current_stage_view.dispatch(request)\n                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n  File \"/authentik/core/sources/stage.py\", line 25, in dispatch\n    connection.save()\n  File \"/ak-root/venv/lib/python3.12/site-packages/django/db/models/base.py\", line 822, in save\n    self.save_base(\n  File \"/ak-root/venv/lib/python3.12/site-packages/django/db/models/base.py\", line 906, in save_base\n    parent_inserted = self._save_parents(\n                      ^^^^^^^^^^^^^^^^^^^\n  File \"/ak-root/venv/lib/python3.12/site-packages/django/db/models/base.py\", line 959, in _save_parents\n    updated = self._save_table(\n              ^^^^^^^^^^^^^^^^^\n  File \"/ak-root/venv/lib/python3.12/site-packages/django/db/models/base.py\", line 1071, in _save_table\n    results = self._do_insert(\n              ^^^^^^^^^^^^^^^^\n  File \"/ak-root/venv/lib/python3.12/site-packages/django/db/models/base.py\", line 1112, in _do_insert\n    return manager._insert(\n           ^^^^^^^^^^^^^^^^\n  File \"/ak-root/venv/lib/python3.12/site-packages/django/db/models/manager.py\", line 87, in manager_method\n    return getattr(self.get_queryset(), name)(*args, **kwargs)\n           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n  File \"/ak-root/venv/lib/python3.12/site-packages/django/db/models/query.py\", line 1847, in _insert\n    return query.get_compiler(using=using).execute_sql(returning_fields)\n           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n  File \"/ak-root/venv/lib/python3.12/site-packages/django/db/models/sql/compiler.py\", line 1823, in execute_sql\n    cursor.execute(sql, params)\n  File \"/ak-root/venv/lib/python3.12/site-packages/sentry_sdk/utils.py\", line 1860, in runner\n    return sentry_patched_function(*args, **kwargs)\n           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n  File \"/ak-root/venv/lib/python3.12/site-packages/sentry_sdk/integrations/django/__init__.py\", line 653, in execute\n    result = real_execute(self, sql, params)\n             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n  File \"/ak-root/venv/lib/python3.12/site-packages/django/db/backends/utils.py\", line 79, in execute\n    return self._execute_with_wrappers(\n           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n  File \"/ak-root/venv/lib/python3.12/site-packages/django/db/backends/utils.py\", line 92, in _execute_with_wrappers\n    return executor(sql, params, many, context)\n           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n  File \"/ak-root/venv/lib/python3.12/site-packages/django/db/backends/utils.py\", line 100, in _execute\n    with self.db.wrap_database_errors:\n         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n  File \"/ak-root/venv/lib/python3.12/site-packages/django/db/utils.py\", line 91, in __exit__\n    raise dj_exc_value.with_traceback(traceback) from exc_value\n  File \"/ak-root/venv/lib/python3.12/site-packages/django/db/backends/utils.py\", line 105, in _execute\n    return self.cursor.execute(sql, params)\n           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n  File \"/ak-root/venv/lib/python3.12/site-packages/django_prometheus/db/common.py\", line 69, in execute\n    return super().execute(*args, **kwargs)\n           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n  File \"/ak-root/venv/lib/python3.12/site-packages/psycopg/cursor.py\", line 97, in execute\n    raise ex.with_traceback(None)\ndjango.db.utils.IntegrityError: duplicate key value violates unique constraint \"authentik_core_usersourc_user_id_source_id_ad1f5aa7_uniq\"\nDETAIL:  Key (user_id, source_id)=(7, 0cdc3c07-6067-436b-b226-b88c899ab917) already exists."}

Version and Deployment (please complete the following information):

• authentik version:2024.12.1
• Deployment: docker compose

Additional context
Add any other context about the problem here.