more friendly error message(s) when offline

[chrisdias]

Testing #141296

When I am offline and search the marketplace, I get the message Error while fetching extensions. XHR failed. We know we are offline, suggest to have a friendlier error message here.

Unable to search the Marketplace when offline, please check your connection. or something like that.

[sandy081]

@joaomoreno / @deepak1556 Is there an API to know if VS Code is offline?

At present, the internal request service does not provide any info about this.

[deepak1556]

In the renderer process you can use the navigator.onLine property and in the main process you can use net.isOnline method.

[sandy081]

[joyceerhl]

I see this in insiders.vscode.dev (PWA and web) still:

[sandy081]

It works for me in insiders.vscode.dev - I turned off wifi for eg.,