Fail virtual ansible merges on a short member versions list

internal/virtual/ansible_merger.go

@@ -160,9 +160,12 @@ func (e *Engine) ansibleMember(ctx context.Context, member, ns, name string) (*A
 		}
 		m.Found = true
 		m.Refs = append(m.Refs, doc.Data...)
-		if remote.RepoType == models.RepoTypeLocal || len(doc.Data) == 0 || len(m.Refs) >= doc.Meta.Count {
+		if remote.RepoType == models.RepoTypeLocal || len(m.Refs) >= doc.Meta.Count {
 			return m, nil
 		}
+		if len(doc.Data) == 0 {
+			return nil, fmt.Errorf("%s/%s: empty page after %d of %d versions", member, path, len(m.Refs), doc.Meta.Count)
+		}
 	}
 	return nil, fmt.Errorf("%s: more than %d pages of %s.%s versions", member, maxAnsibleMemberPages, ns, name)
 }

internal/virtual/ansible_merger_test.go

@@ -139,6 +139,18 @@ func TestAnsibleVersionsFailsClosed(t *testing.T) {
 	}
 }
 
+func TestAnsibleVersionsShortRemote(t *testing.T) {
+	e := ansibleEngine(func(_ models.Remote, path string) ([]byte, error) {
+		if strings.Contains(path, "offset=") {
+			return json.Marshal(map[string]any{"meta": map[string]int{"count": 3}, "data": []any{}})
+		}
+		return galaxyPages([]string{"3.0.0", "2.0.0", "1.0.0"}, path)
+	})
+	if _, err := e.AnsibleVersions(context.Background(), ansibleVirt("galaxy"), "a", "b"); err == nil || errors.Is(err, ErrNotFound) {
+		t.Fatalf("empty page before count: want a non-404 error, got %v", err)
+	}
+}
+
 func TestAnsibleVersionRoutesViaVirtual(t *testing.T) {
 	detail := func(dl string) []byte {
 		b, _ := json.Marshal(map[string]any{"version": "1.0.0", "download_url": dl, "artifact": map[string]string{"sha256": "ab"}})