`ol.xml.pushParseAndPop` uses a template, so its better to write:
```js
var coordinates =  ol.xml.pushParseAndPop(/** @type {Array.<Array.<number>>} */ ([]),
    ol.format.GML.MULTIPOINT_PARSERS_, node, objectStack);
```
By convention, `ol.xml.pushParseAndPop` returns `undefined` if there was an error, so you always have to check if its return value is `undefined`. If it is, you should either return `undefined` yourself (if you're in a read-style function) or ensure that the object stack is not modified (if you're in a parser-style function).