[explore] fix empty chart when changing viz type (#2698)

* [explore] fix empty chart when changing viz type

* Lint

superset/assets/javascripts/explorev2/components/ChartContainer.jsx

@@ -60,6 +60,7 @@ class ChartContainer extends React.PureComponent {
         ) && !this.props.queryResponse.error
         && this.props.chartStatus !== 'failed'
         && this.props.chartStatus !== 'stopped'
+        && this.props.chartStatus !== 'loading'
       ) {
       this.renderViz();
     }