From b2e7c41d64a6dc419f1a5dffd53ee66d8cd841d0 Mon Sep 17 00:00:00 2001
From: Connor Peet <connor@peet.io>
Date: Mon, 28 Sep 2020 15:45:23 -0700
Subject: [PATCH] notebooks: show a more friendly error if preloads fail

Fixes https://github.com/microsoft/vscode/issues/105946
---
 .../view/renderers/backLayerWebView.ts        | 35 ++++++++-----------
 .../browser/view/renderers/webviewPreloads.ts | 26 ++++++++++----
 2 files changed, 35 insertions(+), 26 deletions(-)

diff --git a/src/vs/workbench/contrib/notebook/browser/view/renderers/backLayerWebView.ts b/src/vs/workbench/contrib/notebook/browser/view/renderers/backLayerWebView.ts
index c210fc526d0..8cc06b08600 100644
--- a/src/vs/workbench/contrib/notebook/browser/view/renderers/backLayerWebView.ts
+++ b/src/vs/workbench/contrib/notebook/browser/view/renderers/backLayerWebView.ts
@@ -148,7 +148,8 @@ export interface IFocusOutputMessage {
 }
 
 export interface IPreloadResource {
-	uri: string
+	originalUri: string;
+	uri: string;
 }
 
 export interface IUpdatePreloadResourceMessage {
@@ -800,19 +801,15 @@ var requirejs = (function() {
 		await this._loaded;
 
 		const resources: IPreloadResource[] = [];
-		preloads = preloads.map(preload => {
-			if (this.environmentService.isExtensionDevelopment && (preload.scheme === 'http' || preload.scheme === 'https')) {
-				return preload;
-			}
-			return asWebviewUri(this.environmentService, this.id, preload);
-		});
+		for (const preload of preloads) {
+			const uri = this.environmentService.isExtensionDevelopment && (preload.scheme === 'http' || preload.scheme === 'https')
+				? preload : asWebviewUri(this.environmentService, this.id, preload);
 
-		preloads.forEach(e => {
-			if (!this._preloadsCache.has(e.toString())) {
-				resources.push({ uri: e.toString() });
-				this._preloadsCache.add(e.toString());
+			if (!this._preloadsCache.has(uri.toString())) {
+				resources.push({ uri: uri.toString(), originalUri: preload.toString() });
+				this._preloadsCache.add(uri.toString());
 			}
-		});
+		}
 
 		if (!resources.length) {
 			return;
@@ -833,19 +830,17 @@ var requirejs = (function() {
 		const resources: IPreloadResource[] = [];
 		const extensionLocations: URI[] = [];
 		for (const rendererInfo of renderers) {
-			const preloads = [rendererInfo.entrypoint, ...rendererInfo.preloads]
-				.map(preload => asWebviewUri(this.environmentService, this.id, preload));
 			extensionLocations.push(rendererInfo.extensionLocation);
-
-			preloads.forEach(e => {
-				const resource: IPreloadResource = { uri: e.toString() };
+			for (const preload of [rendererInfo.entrypoint, ...rendererInfo.preloads]) {
+				const uri = asWebviewUri(this.environmentService, this.id, preload);
+				const resource: IPreloadResource = { uri: uri.toString(), originalUri: preload.toString() };
 				requiredPreloads.push(resource);
 
-				if (!this._preloadsCache.has(e.toString())) {
+				if (!this._preloadsCache.has(uri.toString())) {
 					resources.push(resource);
-					this._preloadsCache.add(e.toString());
+					this._preloadsCache.add(uri.toString());
 				}
-			});
+			}
 		}
 
 		if (!resources.length) {
diff --git a/src/vs/workbench/contrib/notebook/browser/view/renderers/webviewPreloads.ts b/src/vs/workbench/contrib/notebook/browser/view/renderers/webviewPreloads.ts
index 4355e350a66..7ff3a7e8e73 100644
--- a/src/vs/workbench/contrib/notebook/browser/view/renderers/webviewPreloads.ts
+++ b/src/vs/workbench/contrib/notebook/browser/view/renderers/webviewPreloads.ts
@@ -308,7 +308,7 @@ function webviewPreloads() {
 	 * Map of preload resource URIs to promises that resolve one the resource
 	 * loads or errors.
 	 */
-	const preloadPromises = new Map<string, Promise<void>>();
+	const preloadPromises = new Map<string, Promise<string | undefined /* error string, or undefined if ok */>>();
 	const queuedOuputActions = new Map<string, Promise<void>>();
 
 	/**
@@ -341,7 +341,7 @@ function webviewPreloads() {
 		switch (event.data.type) {
 			case 'html':
 				enqueueOutputAction(event.data, async data => {
-					await Promise.all(data.requiredPreloads.map(p => preloadPromises.get(p.uri)));
+					const preloadErrs = await Promise.all(data.requiredPreloads.map(p => preloadPromises.get(p.uri)));
 					if (!queuedOuputActions.has(data.outputId)) { // output was cleared while loading
 						return;
 					}
@@ -378,6 +378,18 @@ function webviewPreloads() {
 						outputNode.innerHTML = content.htmlContent;
 						cellOutputContainer.appendChild(outputNode);
 						domEval(outputNode);
+					} else if (preloadErrs.some(e => !!e)) {
+						outputNode.innerText = `Error loading preloads:`;
+						const errList = document.createElement('ul');
+						for (const err of preloadErrs) {
+							if (err) {
+								const item = document.createElement('li');
+								item.innerText = err;
+								errList.appendChild(item);
+							}
+						}
+						outputNode.appendChild(errList);
+						cellOutputContainer.appendChild(outputNode);
 					} else {
 						onDidCreateOutput.fire([data.apiNamespace, {
 							element: outputNode,
@@ -465,13 +477,15 @@ function webviewPreloads() {
 				const resources = event.data.resources;
 				const preloadsContainer = document.getElementById('__vscode_preloads')!;
 				for (let i = 0; i < resources.length; i++) {
-					const { uri } = resources[i];
+					const { uri, originalUri } = resources[i];
 					const scriptTag = document.createElement('script');
 					scriptTag.setAttribute('src', uri);
 					preloadsContainer.appendChild(scriptTag);
-					preloadPromises.set(uri, new Promise<void>(resolve => {
-						scriptTag.addEventListener('load', () => resolve());
-						scriptTag.addEventListener('error', () => resolve());
+					preloadPromises.set(uri, new Promise<string | undefined>(resolve => {
+						scriptTag.addEventListener('load', () => resolve(undefined));
+						scriptTag.addEventListener('error', () =>
+							resolve(`Network error loading ${originalUri}, does the path exist?`)
+						);
 					}));
 				}
 				break;