Be defensive against invalid sizes

Author: lionel-

src/vs/workbench/contrib/positronPlots/browser/components/dynamicPlotInstance.tsx

@@ -51,6 +51,12 @@ export const DynamicPlotInstance = (props: DynamicPlotInstanceProps) => {
 		const ratio = DOM.getActiveWindow().devicePixelRatio;
 		const disposables = new DisposableStore();
 
+		// The frontend shoudn't send invalid sizes so be defensive. Sometimes the
+		// plot container is in a strange state when it's hidden.
+		if (props.height <= 0 || props.width <= 0) {
+			return;
+		}
+
 		// If the plot is already rendered, use the old image until the new one is ready.
 		if (props.plotClient.lastRender) {
 			setUri(props.plotClient.lastRender.uri);

src/vs/workbench/contrib/positronPlots/browser/components/plotsContainer.tsx

@@ -63,8 +63,8 @@ export const PlotsContainer = (props: PlotContainerProps) => {
 
 	const historyPx = props.showHistory ? HistoryPx : 0;
 	const historyEdge = historyBottom ? 'history-bottom' : 'history-right';
-	const plotHeight = historyBottom ? props.height - historyPx : props.height;
-	const plotWidth = historyBottom ? props.width : props.width - historyPx;
+	const plotHeight = historyBottom && props.height > 0 ? props.height - historyPx : props.height;
+	const plotWidth = historyBottom || props.width <= 0 ? props.width : props.width - historyPx;
 
 	useEffect(() => {
 		// Ensure the selected plot is visible. We do this so that the history
@@ -87,6 +87,11 @@ export const PlotsContainer = (props: PlotContainerProps) => {
 	}, [plotHistoryRef]);
 
 	useEffect(() => {
+		// Be defensive against null sizes when pane is invisible
+		if (plotWidth <= 0 || plotHeight <= 0) {
+			return;
+		}
+
 		// Propagate current render settings. Use a debouncer to avoid excessive
 		// messaging to language kernels.
 		const debounceTimer = setTimeout(() => {

src/vs/workbench/contrib/positronPlots/browser/positronPlots.tsx

@@ -135,7 +135,7 @@ export const PositronPlots = (props: PropsWithChildren<PositronPlotsProps>) => {
 			<ActionBars {...props} zoomHandler={zoomHandler} zoomLevel={zoom} />
 			<PlotsContainer
 				darkFilterMode={darkFilterMode}
-				height={height - 34}
+				height={height > 0 ? height - 34 : 0}
 				positronPlotsService={props.positronPlotsService}
 				showHistory={showHistory}
 				visible={visible}