Describe the bug
I get an empty SAML Error description "Failed to process SAML assertion: "
In the source authentik/providers/saml/views/flows.py there is:

        try:
            response = AssertionProcessor(provider, request, auth_n_request).build_response()
        except SAMLException as exc:
            Event.new(
                EventAction.CONFIGURATION_ERROR,
                message=f"Failed to process SAML assertion: {str(exc)}",
                provider=provider,
            ).from_http(self.request)
            return self.executor.stage_invalid()

The issue is that {str(exc}} is an empty string.
I think that is because SAMLException has no str method as a look
in the source authentik/sources/saml/exceptions.py reveals:

class SAMLException(SentryIgnoredException):
    """Base SAML Exception"""

Expected behavior
The SAML error message should be clear about what the error actually is.

Screenshots
The screen shows me an Authentik User consent with Message "Request denied"

Logs
authentik-server-1 | {"action": "configuration_error", "auth_via": "session", "client_ip": "10.0.0.15", "context": {"http_request": {"args": {"RelayState": "https://zabbix.domain/index_sso.php", "SAMLRequest": "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", "inspector": "available"}, "method": "GET", "path": "/api/v3/flows/executor/default-provider-authorization-implicit-consent/", "request_id": "8b80e1429b3f416990635973e3dfe303", "user_agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:136.0) Gecko/20100101 Firefox/136.0"}, "message": "Failed to process SAML assertion: ", "provider": {"app": "authentik_providers_saml", "model_name": "samlprovider", "name": "Zabbix", "pk": 11}}, "domain_url": "authentik.domain", "event": "Created Event", "host": "authentik.domain", "level": "info", "logger": "authentik.events.models", "pid": 75, "request_id": "8b80e1429b3f416990635973e3dfe303", "schema_name": "public", "timestamp": "2025-03-20T08:19:52.831175", "user": {"email": "email@domain", "pk": 7, "username": "username"}}

Version and Deployment (please complete the following information):

• authentik version: 2025.2.2
• Deployment: docker-compose

Additional context
I use a Let's Encrypt wildcard certificate created with acme.