fix: answer an empty checklist with an empty items list

checklists_postgres_test.go

@@ -43,6 +43,9 @@ func TestChecklistsAgainstDatabase(t *testing.T) {
 	created := obj(alice.want(http.StatusCreated, "POST", base+"/checklists",
 		`{"title":"Zjazd 1","meeting_id":`+jsonID(meeting.ID)+`}`)["data"])
 	cid := id(created["id"])
+	if items, ok := created["items"].([]any); !ok || len(items) != 0 {
+		t.Errorf("new checklist items = %v, want []", created["items"])
+	}
 	if obj(created["meeting"])["number"] != float64(meeting.Number) {
 		t.Errorf("meeting = %v", created["meeting"])
 	}