Change websocket mock from empty object to empty class (#3998)

web/components/layouts/Main/Main.stories.tsx

@@ -41,7 +41,7 @@ export default meta;
 
 // mock the Websocket to prevent ani webhook calls from being made in storybook
 // @ts-ignore
-window.WebSocket = () => {};
+window.WebSocket = class {};
 
 type StateInitializer = (mutableState: MutableSnapshot) => void;