Let Express log HTTP handler errors

Express already comes with a built-in error handler that is attached
as the last middleware. Any handler or middleware can pass an Error
object (with an optional `.status` or `.statusCode` property set to a
4xx or 5xx code) to `next()` and Express will both log a detailed
error message and display a useful error message to the user. For more
details see "The default error handler" at:
https://expressjs.com/en/guide/error-handling.html

src/ep.json

@@ -74,12 +74,6 @@
         "expressCreateServer": "ep_etherpad-lite/node/hooks/express/importexport"
       }
     },
-    {
-      "name": "errorhandling",
-      "hooks": {
-        "expressCreateServer": "ep_etherpad-lite/node/hooks/express/errorhandling"
-      }
-    },
     {
       "name": "socketio",
       "hooks": {

src/node/hooks/express.js

@@ -1,6 +1,7 @@
 'use strict';
 
 const _ = require('underscore');
+const assert = require('assert').strict;
 const cookieParser = require('cookie-parser');
 const events = require('events');
 const express = require('express');
@@ -113,6 +114,13 @@ exports.restartServer = async () => {
   }
 
   app.use((req, res, next) => {
+    // This stats logic should be in the first middleware to ensure that no other middleware can
+    // prevent the stats from being updated.
+    res.on('finish', () => {
+      assert(res.statusCode);
+      stats.meter(`http${res.statusCode}`).mark();
+    });
+
     // res.header("X-Frame-Options", "deny"); // breaks embedded pads
     if (settings.ssl) {
       // we use SSL

src/node/hooks/express/errorhandling.js

@@ -1,19 +0,0 @@
-'use strict';
-
-const stats = require('../../stats');
-
-exports.expressCreateServer = (hook_name, args, cb) => {
-  exports.app = args.app;
-
-  // Handle errors
-  args.app.use((err, req, res, next) => {
-    // if an error occurs Connect will pass it down
-    // through these "error-handling" middleware
-    // allowing you to respond however you like
-    res.status(500).send({error: 'Sorry, something bad happened!'});
-    console.error(err.stack ? err.stack : err.toString());
-    stats.meter('http500').mark();
-  });
-
-  return cb();
-};