Only show overlay if container is set (#4601)

* Pass width in props

* Only load overlay if container is set

superset/assets/javascripts/chart/Chart.jsx

@@ -223,6 +223,7 @@ class Chart extends React.PureComponent {
           !this.props.chartAlert &&
           this.props.refreshOverlayVisible &&
           !this.props.errorMessage &&
+          this.container &&
           <RefreshChartOverlay
             height={this.height()}
             width={this.width()}