Gracefully handle cached assignment with no policy found

src/vmod_hoailona.c

@@ -642,6 +642,11 @@ get_policy(VRT_CTX, const struct vmod_priv * restrict const priv_task,
 		return task->policy;
 	}
 
+	if (task->assignment == NULL) {
+		VERR(ctx, "%s.%s() no policy", vcl_name, method);
+		return NULL;
+	}
+
 	CHECK_OBJ_NOTNULL(task->assignment, VMOD_HOAILONA_ASSIGNMENT_MAGIC);
 	CHECK_OBJ_NOTNULL(task->assignment->policy, VMOD_HOAILONA_POLICY_MAGIC);
 	return task->assignment->policy;