Fix cannot update (#5890)

src/server/web/views/flash.pug

@@ -0,0 +1,20 @@
+doctype html
+
+html
+	script.
+		localStorage.removeItem('locale');
+
+		try {
+			navigator.serviceWorker.controller.postMessage('clear');
+
+			navigator.serviceWorker.getRegistrations().then(registrations => {
+				return Promise.all(registrations.map(registration => registration.unregister()));
+			}).then(() => {
+				location = '/';
+			});
+		} catch (e) {
+			console.error(e);
+			setTimeout(() => {
+				location = '/';
+			}, 10000)
+		}