The reason for the using Symbol is incase of matching variable for other plugins or class instance.
Note you need to config gun plugin the default config.
app.use(gunPlugin,{
peers:['http://localhost:3000/gun']
, localStorage: false
, isDebug:true
});
Need to add some packages as buffer as it seem to be bug in vue set up. As well the window variable since it front end client.
If using SSR need be sure that window, document is config in some ways.