Merging in PR results in blank webview

[rzhao271]

On the latest Insiders on Windows, I just squash-merged a PR with the GHPRI extension.
Immediately, the webview went blank, and the devtools console showed the following error:

webview-pr-description.js:1789 TypeError: Cannot read properties of undefined (reading 'toLocaleString')
    at Timestamp (webview-pr-description.js:1807:73534)
    at oh (webview-pr-description.js:1789:52351)
    at Rj (webview-pr-description.js:1791:8430)
    at Qj (webview-pr-description.js:1791:945)
    at Kj (webview-pr-description.js:1791:848)
    at yj (webview-pr-description.js:1789:89341)
    at webview-pr-description.js:1789:38865
    at M.unstable_runWithPriority (webview-pr-description.js:1805:4128)
    at cg (webview-pr-description.js:1789:38531)
    at fg (webview-pr-description.js:1789:38811)
Ci @ webview-pr-description.js:1789
webview-pr-description.js:1807 Uncaught (in promise) TypeError: Cannot read properties of undefined (reading 'toLocaleString')
    at Timestamp (webview-pr-description.js:1807:73534)
    at oh (webview-pr-description.js:1789:52351)
    at Rj (webview-pr-description.js:1791:8430)
    at Qj (webview-pr-description.js:1791:945)
    at Kj (webview-pr-description.js:1791:848)
    at yj (webview-pr-description.js:1789:89341)
    at webview-pr-description.js:1789:38865
    at M.unstable_runWithPriority (webview-pr-description.js:1805:4128)
    at cg (webview-pr-description.js:1789:38531)
    at fg (webview-pr-description.js:1789:38811)