RUNTIME ERROR: Object assertion failed.
	error.obj_assert.fail1.jsonnet:20:23-29	thunk <object_assert>
	std.jsonnet:1307:42-46	thunk <a>
	std.jsonnet:1307:42-54	function <anonymous>
	std.jsonnet:1307:42-54	function <anonymous>
	std.jsonnet:1311:11-23	
