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/middleware/index.js

@@ -3,6 +3,7 @@
 exports = module.exports = {
     cookieParser: require('cookie-parser'),
     cors: require('./cors.js'),
+    json: require('./json.js'),
     lastMile: require('connect-lastmile'),
     multipart: require('./multipart.js'),
     timeout: require('connect-timeout')