Fix demo again

addons/xterm-addon-canvas/src/CanvasAddon.ts

@@ -25,7 +25,9 @@ export class CanvasAddon extends Disposable implements ITerminalAddon {
   public activate(terminal: Terminal): void {
     const core = (terminal as any)._core;
     if (!terminal.element) {
-      this.register(core.onWillOpen(() => this.activate(terminal)));
+      this.register(toDisposable(() => {
+        core.onWillOpen(() => this.activate(terminal));
+      }));
       return;
     }
 

addons/xterm-addon-webgl/src/WebglAddon.ts

@@ -33,7 +33,9 @@ export class WebglAddon extends Disposable implements ITerminalAddon {
     }
     const core = (terminal as any)._core;
     if (!terminal.element) {
-      this.register(core.onWillOpen(() => this.activate(terminal)));
+      this.register(toDisposable(() => {
+        core.onWillOpen(() => this.activate(terminal));
+      }));
       return;
     }
     this._terminal = terminal;

demo/client.ts

@@ -271,11 +271,16 @@ function createTerminal(): void {
   socketURL = protocol + location.hostname + ((location.port) ? (':' + location.port) : '') + '/terminals/';
 
   addons.fit.instance!.fit();
-  typedTerm.loadAddon(addons.webgl.instance);
-  setTimeout(() => {
-    addTextureAtlas(addons.webgl.instance.textureAtlas);
-    addons.webgl.instance.onChangeTextureAtlas(e => addTextureAtlas(e));
-  }, 0);
+  try { // try-catch to allow the demo to load if webgl is not supported
+    typedTerm.loadAddon(addons.webgl.instance);
+    setTimeout(() => {
+      addTextureAtlas(addons.webgl.instance.textureAtlas);
+      addons.webgl.instance.onChangeTextureAtlas(e => addTextureAtlas(e));
+    }, 0);
+  }
+  catch {
+    addons.webgl.instance = undefined;
+  }
 
   term.open(terminalContainer);
   term.focus();