there is no logging or notification going on when the resolution of the shell environment takes long or fails, making it hard for us to find out about these issues (e.g. the window is just blank and dev tools shows nothing)

Yes, ideally the resolving of the environment finishes without errors and in a timely fashion. The current implementation is done like that because we statically reference process.env in our code and cannot do that unless we block loading code which has negative performance implications.

we seem to not resolve any environment on Windows and also not when process.env['VSCODE_CLI'] is set so I would expect we can skip this call on the renderer side and save us the inter process communication on startup in those cases

We don't need to.

The fix will be to log an error to the console and to simply continue with a potential incomplete environment

The lazyEnv-promise behaves actually like that. It's getShellEnvironment that doesn't finish

getShellEnvironment().then(shellEnv => {
	win.webContents.send('vscode:acceptShellEnv', shellEnv);
}, err => {
	win.webContents.send('vscode:acceptShellEnv', {});
	console.error('Error fetching shell env', err);
});

Timeout apparently wasn't the way to go

Increased the timeout to 10s. Let's add some perf numbers to know exactly how long does the renderer wait for that env to come.