Crashing worker in web extension host brings down the entire extension host

[mjbvz]

Steps to Reproduce:

1. yo code --insiders and create a web extension
2. In the main extension.ts, spawn a worker:

declare const Worker: any;

export function activate(context: vscode.ExtensionContext) {
    const workWorkWork = new Worker(vscode.Uri.joinPath(context.extensionUri, 'crashy-worker.js'));
}

3. Create crashy-worker.js at the top level of the extension:

throw new Error('Worker error') 

4. F5 and then activate the extension

Bug
The worker exception brings down the entire extension host. While debugging with F5, this causes the entire window to close without any useful error logs

[jrieken]

Something similar happens even without a dedicated worker, e.g have the snippet below and see the extension host terminate

vscode.commands.registerCommand('web-ext.helloWorld', () => {
	setTimeout(() => { throw new Error('RANDOM'); });
	console.log('WAIT for it');
});

This is because the onerror-handler is very strict simply triggers an exit, see

vscode/src/vs/workbench/services/extensions/browser/webWorkerExtensionHost.ts

Lines 287 to 290 in d18e54f

	(event: any) => {
	console.error(event.message, event.error);
	this._onDidExit.fire([ExtensionHostExitCode.UnexpectedError, event.message || event.error]);
	}

I will push a change to only terminate the web extension host when uncaught errors happen during worker-start