feat: rate limit error chaching (#2448)

* feat: rate limit error chaching

Rate limit error caching to alleviate PATs.

* refactor: improve code comments

api/gist.js

@@ -77,7 +77,12 @@ export default async (req, res) => {
       }),
     );
   } catch (err) {
-    res.setHeader("Cache-Control", `no-cache, no-store, must-revalidate`); // Don't cache error responses.
+    res.setHeader(
+      "Cache-Control",
+      `max-age=${CONSTANTS.ERROR_CACHE_SECONDS / 2}, s-maxage=${
+        CONSTANTS.ERROR_CACHE_SECONDS
+      }, stale-while-revalidate=${CONSTANTS.ONE_DAY}`,
+    ); // Use lower cache period for errors.
     return res.send(renderError(err.message, err.secondaryMessage));
   }
 };