Dev bundle unable to deal with uncaught exceptions

[jbellis]

With the dev bundle, uncaught exceptions result in a stack trace like this:

Notably, all the information about the exception that caused this is lost -- it dies trying to load java.lang.Exception before it can show anything.

With the non-dev bundle it works as expected and I get

Uncaught Error: Class$obf_1001: rte
    at helloworld.js:2

Ideally the dev bundle would do the same, only preserving type names.

I copied helloworld_dev_js.map into my html directory as well, but it is looking for HelloWorld.js.map instead which is not an artifact present in bazel-bin.

Here is my modification of the hello world example to throw a RuntimeException. To run it, I copied helloworld_dev.js and helloworld_dev_js.map into the html directory but I did not commit them. I note that it is looking for HelloWorld.js.map but that is not an artifact present in bazel-bin.

[gkdn]

Thanks for the detailed report. It's helpful.

There is something fishy here. I see that it is trying to use debug loader but it shouldn't (which is slow and has bunch of problems). By any chance you have a custom setup? Your repro also uses custom setup so it is not surprising that one is using the debug loader.

[gkdn]

To check this with your repro, could you follow the instructions in https://github.com/google/j2cl/blob/master/docs/getting-started.md instead of custom html page?

[jbellis]

with bazel run src/main/java/com/google/j2cl/samples/helloworld:helloworld_dev_server, I get Uncaught Error: java.lang.RuntimeException: rte as desired.

What is the correct way to use j2cl with a custom setup?

[gkdn]

Please see j2cl_application.bzl documentation for providing/using custom host page for the dev server.

If you need use your own server, you can try to replicate those instructions (link importing <target>_dev.html) or you can manually load <target>_dev_config.js in addition to <target>_dev.js in your page.

[jbellis]

Confirmed that adding helloworld_dev_config.js to my page fixes the problem. Thank you!

Where would it be appropriate to mention this in the docs?

[gkdn]

I think it depends on where you have found out about the <target>_dev.js. I think it is only documented in j2cl_application so we can improve the documentation there.

[gkdn]

Ahh! The target in helloworld mentions it in the section starting with "It provides couple of convenient targets"

I think we should remove the mention of dev.js and point the right place (even it is not complete). I will send a patch.

[jbellis]

Thank you!