Error in logs when PR description webview is sitting open with Enterprise server

[alexr00]

1. Make sure githubPullRequests.webviewRefreshInterval is set to something reasonable small. The default 60 is fine.
2. Open a folder containing a GitHub Enterprise Server repo
3. Open a PR description webview
4. Wait the interval specified in step 1
5. 🐛 an error will show in the logs