Fix crash with express 5

express.json does not enforce json. this means it will pass it through
but let req.body be undefined. this causes all our asserts to crash

src/server.js

@@ -41,7 +41,7 @@ async function initializeExpressSync() {
 
     const REQUEST_TIMEOUT = 60000; // timeout for all requests (see also setTimeout on the httpServer)
 
-    const json = express.json({ strict: true, limit: QUERY_LIMIT }); // application/json
+    const json = middleware.json({ strict: true, limit: QUERY_LIMIT }); // forces json content-type
 
     app.set('json spaces', 2); // pretty json
     app.enable('trust proxy'); // trust the X-Forwarded-* headers