`Uncaught TypeErrror` in browser console after upgrading to 3.3.3

After upgrading from 3.3.2 to 3.3.3 I started seeing error messages in the browser console on startup. The message is of the form Uncaught TypeError: f$1 is not a function.

One of the lines of code in the callstack is

hardExit$3.apply$mcVI$sp__I__V(c.Lcats_effect_ExitCode__f_code)

With the line above it is:

var c = $j_cats$002eeffect$002eExitCode.$as_Lcats_effect_ExitCode(c$2);
 hardExit$3.apply$mcVI$sp__I__V(c.Lcats_effect_ExitCode__f_code)

This looks similar to this line of code from #2707: https://github.com/typelevel/cats-effect/blob/614e98982602263d1447f3a9975be84bb4c23a67/core/js/src/main/scala/cats/effect/IOApp.scala#L243

I haven’t been able to verify it is the problem, but the cats effect upgrade is the only change. If needed, I could try to create a minimal example. The application it is occurring in does not qualify as simple…

[toddburnside]

I’m probably not going to get a chance to look at it tonight, but I’ll try to reproduce it in the morning.

[armanbilge]

@cquiroz yes, process is a tricky one. We mostly use it so that IOApp on Node.js can behave like the JVM: command line args, signal handlers, exit hooks, etc.

But, process.env specifically has become a sort of pseudo-standard across web frameworks as well:

• https://create-react-app.dev/docs/adding-custom-environment-variables/
• https://webpack.js.org/plugins/environment-plugin/
• https://vitejs.dev/guide/env-and-mode.html#production-replacement

Enough so, that we also use it for configuring the CE runtime on JS: https://typelevel.org/cats-effect/docs/scaling-and-tuning/io-runtime-config#js

So, we have to resort to js.Dynamic and Try when working with process, and rely on our test suite to make sure we didn’t forget any Try 😬

Maybe a more robust approach would be to first detect globally if we are running in Node.js, and then use that to decide whether or not to do all those Node.js-only process things. Then if we forget to wrap something in a Try like I did here it is much less likely to create a problem.

val isNodeJSRuntime = Try(
  js.Dynamic.global.process.release.name.asInstanceOf[String]
).toOption.exists(_ == "node")