The client's browser is always informed whenever something bad happens on the server and an uncatched exception is thrown.
We can simulate that quite easily. Just create a new application and add the following code there:
protected void init(VaadinRequest request) { VaadinService service = request.getService(); DeploymentConfiguration deploymentConfiguration = service.getDeploymentConfiguration(); boolean productionMode = deploymentConfiguration.isProductionMode(); if (productionMode) { ProductionErrorHandler errorHandler = new ProductionErrorHandler(); setErrorHandler(errorHandler); } final VerticalLayout layout = new VerticalLayout(); layout.setMargin(true); setContent(layout); Button button = new Button("Throw an error please"); button.addClickListener(new Button.ClickListener() { public void buttonClick(ClickEvent event) { layout.addComponent(new Label("Click and bang!")); throw...