My chatting application just broke. When I press Enter to send a message, it refreshes the page and navigates to ?. Then if I try again, it'll simply throw an exception:

EXCEPTION: TypeError: Instance of 'eE': type 'eE' is not a subtype of type 'minified:G'

I tried outputting SourceMaps by putting this in my build.yaml:

targets:
  $default:
    builders:
      build_web_compilers|dart_source_cleanup:
        release_options:
          enabled: false

It didn't work.

So I compiled with no obfuscation with this configuration:

targets:
  $default:
    builders:
      build_web_compilers|entrypoint:
        generate_for:
        - web/**.dart
        options:
          dart2js_args:
            - --no-minify
            - -O4

This time the error was readable:

EXCEPTION: NoSuchMethodError: method not found: 'preventDefault$0' (J.getInterceptor$x(...).preventDefault$0 is not a function)
STACKTRACE: 
TypeError: J.getInterceptor$x(...).preventDefault$0 is not a function
    at Object.preventDefault$0$x (http://localhost:8080/main.dart.js:2952:43)
    at NgForm.onSubmit$1 (http://localhost:8080/main.dart.js:30792:11)
    at Object.eval (eval at Closure_forwardInterceptedCallTo (http://localhost:8080/main.dart.js:1431:14), <anonymous>:3:38)
    at RenderView_eventHandler1__closure.call$0 (http://localhost:8080/main.dart.js:28306:27)

I eventually found someone who posted the same issue at https://github.com/dart-lang/angular/issues/1889. It was filed 12 hours ago.

For now I found a workaround at https://stackoverflow.com/a/53954487, which is to not obfuscate by building using the following command:

webdev build --no-release

It uses the DDC compiler instead of dart2js. It produces unminified Javascript, but at least it runs without any issue.

One caveat is that this version reads all of the files from /build/packages, so you'll have to serve all these on your server. A second caveat is that the app will load /require.js instead of ./require.js, meaning that you have to serve your webapp and /packages at the root of your server.