Now, if the first pusher request fails, a waiting message will be displayed and the application will reconnect when the pusher comes back alive or the network connection is established again.
This error message should be used for non fatal errors (otherwise, use the ErrorScene).
It is implemented using Svelte and the new "$errorStore".
Use `errorStore.addErrorMessage` to display the error popup with the message.
This PR uses this error message to display a popup explaining the browser is too old for WebRTC.
