step 9.5: wip (not ticked)

src/app.js

@@ -112,6 +112,8 @@ function createApp() {
   app.use(express.static('public'));
   app.use((err, _req, res, _next) => {
     // Log stack traces server-side only
+    const fs = require('fs');
+    fs.appendFileSync('/tmp/emberfall-errors.log', `ERROR: ${err.constructor.name} | ${err.message} | stack:${err.stack ? 'yes' : 'no'} | keys:${JSON.stringify(Object.keys(err))}\n${err.stack || ''}\n`);
     if (err.stack) {
       console.error(err.stack);
     }