findings-report-api: fix 404 errors

dojo/api_v2/views.py

@@ -11,7 +11,8 @@
 from django.contrib.auth.models import Permission
 from django.core.exceptions import ValidationError
 from django.db import IntegrityError
-from django.http import FileResponse, Http404, HttpResponse
+from django.db.models.query import QuerySet as DjangoQuerySet
+from django.http import FileResponse, HttpResponse
 from django.shortcuts import get_object_or_404
 from django.utils import timezone
 from django_filters.rest_framework import DjangoFilterBackend
@@ -2814,16 +2815,19 @@ def report_generate(request, obj, options):
             ),
         )
 
-    elif type(obj).__name__ == "CastTaggedQuerySet":
+    elif isinstance(obj, DjangoQuerySet):
+        # Support any Django QuerySet (including Tagulous CastTaggedQuerySet)
         findings = report_finding_filter_class(
             request.GET,
             queryset=prefetch_related_findings_for_report(obj).distinct(),
         )
 
         report_name = "Finding"
-
     else:
-        raise Http404
+        obj_type = type(obj).__name__
+        msg = f"Report cannot be generated for object of type {obj_type}"
+        logger.warning(msg)
+        raise ValidationError(msg)
 
     result = {
         "product_type": product_type,