Fix #244 Disable buffer for comments

Comments for an episode are sent back to the front end using
chunked Transfer Enconding, but that that is not supported
on HTTP/2 which is used by the reverse proxy (nginx).

At the moment nginx buffers the chunks before sending them
to the browser, which breaks the way the chunks are processed.

With this commit, we use the header X-Accel-Buffering to
disable this buffering, which worked in local testing.

We should still add a more clear chunk delimiter so that
any other buffering or unknown edge case will not
break the comments function (increase robustness).

Co-authored-by: ericpp

server/index.js

@@ -137,6 +137,10 @@ app.use('/api/comments/byepisodeid', async (req, res) => {
     const cache = new InMemoryCache();
     const fetcher = makeRateLimitedFetcher(fetch);
 
+    // Disable buffering in the nginx server so that the delivery of
+    // chunks are not delayed
+    res.setHeader('X-Accel-Buffering', 'no');
+
     const sentCommenters = {};
 
     const threadcap = await makeThreadcap(socialInteract[0].uri, { userAgent, cache, fetcher });