Do not attempt to close _ws when it's null
Do not attempt to close _ws when it's null

This happens after _onWSClose calls _updateStatus('dead'), because _ws is null at that point.

jupyter/jupyter-js-services,blink1073/jupyter-js-services,blink1073/jupyter-js-services,blink1073/services,jupyterlab/services,jupyter/jupyter-js-services,jupyterlab/services,blink1073/services,blink1073/jupyter-js-services,blink1073/services,blink1073/jupyter-js-services,jupyter/jupyter-js-services,jupyterlab/services,blink1073/services,jupyterlab/services,jupyter/jupyter-js-services