Merge pull request #4193 from silamon/fixdemoagain

Fix demo again

demo/client.ts

@@ -273,11 +273,18 @@ function createTerminal(): void {
   addons.fit.instance!.fit();
   typedTerm.loadAddon(addons.webgl.instance);
   setTimeout(() => {
-    addTextureAtlas(addons.webgl.instance.textureAtlas);
-    addons.webgl.instance.onChangeTextureAtlas(e => addTextureAtlas(e));
+    if (addons.webgl.instance !== undefined) {
+      addTextureAtlas(addons.webgl.instance.textureAtlas);
+      addons.webgl.instance.onChangeTextureAtlas(e => addTextureAtlas(e));
+    }
   }, 0);
 
-  term.open(terminalContainer);
+  try { // try-catch to allow the demo to load if webgl is not supported
+    term.open(terminalContainer);
+  }
+  catch {
+    addons.webgl.instance = undefined;
+  }
   term.focus();
 
   addDomListener(paddingElement, 'change', setPadding);

src/browser/Terminal.ts

@@ -515,7 +515,10 @@ export class Terminal extends CoreTerminal implements ITerminal {
     // Performance: Add viewport and helper elements from the fragment
     this.element.appendChild(fragment);
 
-    this._onWillOpen.fire(this.element);
+    try {
+      this._onWillOpen.fire(this.element);
+    }
+    catch { /* fails to load addon for some reason */ }
     if (!this._renderService.hasRenderer()) {
       this._renderService.setRenderer(this._createRenderer());
     }