To users of early versions of Windows 10:
On Windows 10 PCs Microsoft Edge WebView2 Runtime needs to be installed.
1. Search “Start > Settings > Apps > Apps & features” for “Microsoft Edge WebView2 Runtime”.
2. If it's not found there, download “Evergreen Bootstrapper” from the following URL:
https://developer.microsoft.com/microsoft-edge/webview2
3. Right-click the downloaded file and select “Run as administrator” to execute it.