The purposely broken ToDoMVC is available here.
The first item in the stack trace is:
The source is listed as ../js/app.jsx, which is the file that our compiled and minified js was built from. You can see this file in the ‘Resources’ tab of DevTools, which is generated by Chrome from the minified js coupled with its corresponding map file.
BugReplay checks the server to see if map files exist when saving console logs, and if so, will use them to generate the correct file-name and line numbers based on the code in the original file.
If I open my local copy of js/app.jsx, the line it is complaining about is:
As you can see, the error is occurring on line 58 of the jsx file, where there’s a fairly obvious but very common problem: I’ve referred to the ‘event’ variable as ‘evnt.’
Here is the same issue, but without source map files on the server.
The error itself is still clear, but the stack trace line number is useless due to the JSX compilation and minification.