Detect when the user closes the chart.
Detect when the user closes the chart.

If the chart has been closed a container not found error is
thrown. Detect that the container no longer exists and skip updating
the chart.

GENI-NSF/geni-demoviz,GENI-NSF/geni-demoviz,GENI-NSF/geni-demoviz,GENI-NSF/geni-demoviz