Fix issue with sendBeacon request.

lib/request.js

@@ -86,3 +86,11 @@ export async function getClientInfo(req, { screen }) {
 
   return { userAgent, browser, os, ip, country, device };
 }
+
+export function getJsonBody(req) {
+  if (req.headers['content-type'].indexOf('text/plain') !== -1) {
+    return JSON.parse(req.body);
+  }
+
+  return req.body;
+}