Debugging flutter web source maps! in production build

[jlubeck]

I'm having a problem which only happens in the production build of my web app. Debug works fine, so I can't use the debugger. How should I approach the problem?

I'm getting a Stack Overflow error in the console:

Stack Overflow
main.dart.js:2979     at HF.toString (https://site.com/main.dart.js:28445:33)
main.dart.js:2979     at HF.j (https://site.com/main.dart.js:24342:24)
main.dart.js:2979     at HF.toString (https://site.com/main.dart.js:28445:33)
main.dart.js:2979     at HF.j (https://site.com/main.dart.js:24342:24)
main.dart.js:2979     at HF.toString (https://site.com/main.dart.js:28445:33)
main.dart.js:2979     at HF.j (https://site.com/main.dart.js:24342:24)
main.dart.js:2979     at HF.toString (https://site.com/main.dart.js:28445:33)

But of course that's the minified code and I don't see any source maps that were generated during build so I can understand what's going on.

[iapicca]

@jlubeck
I'm not sure what you mean, but
if you want to run it locally you use dhttpd following these steps

1. install Dart SDK
2. update your path
3. run

pub global activate dhttpd
cd <app directory>
flutter build web --release
cd build/web
dhttpd --port 8888

4. paste localhost:8888 in your browser

[jlubeck]

Hey @iapicca no, I don't mean to run it locally. I mean, how can I debug an error on a production release.

With other frameworks, you would usually get a source map of the minified js file, so you can still know where exactly in your source code the error is happening. But without source maps, it's impossible.

So, is there either a way to export source maps when compiling the release version of the web app? Or export without minifying? Or some other way to to know what is going on with the crash that is not reproducible on debug mode?

[mmmcorpsvit]

you can use sentry

[jlubeck]

@mmmcorpsvit sentry seems to have the same problem: https://stackoverflow.com/questions/58049219/is-it-possible-to-upload-the-flutter-source-maps-or-source-code-to-sentry-for-be

[jlubeck]

I just tried running flutter run --release but can't duplicate the crash there either...

[jlubeck]

ok, interesting bit.
I realized that running flutter run --release actually does create the source maps! And like I said, my app didn't crash. So I just uploaded that and now my site is working.

But if I run flutter build web --release instead, it DOESN"T create source maps, and my app crashes at one point.

So I don't know what's the difference in those 2 commands, but one of them is busted somehow...

[ferhatb]

@jlubeck we are looking at issue. For now, to debug your production build with unminified symbols, try --profile