Scala.js js.dynamicImport always outputs "stub" error

[hugo-vrijswijk]

Compiler version

Any, tested fom 3.0.0 to 3.2.1-RC1-bin-20220717-5c43324-NIGHTLY. Behaviour does not occur on 2.13.8.

Minimized code

import scala.scalajs.js

object Main {
  def main(args: Array[String]): Unit = {
    // Message is dynamically imported and results in a `import(...) call in JS`
    js.dynamicImport {
      println(new Message().msg)
    }
  }
}

class Message {
  def msg = "Hello world dynamic import"
}

Needs some linker config settings to support ES modules. Repro here in a sbt project: https://github.com/hugo-vrijswijk/scala-js-dynamic-import-scala3-bug

Output

[info] Running Main.
<ref *1> $c_jl_Error [java.lang.Error]: stub
    at $c_LMain$.main__AT__V (file:///project/target/scala-3.2.1-RC1-bin-20220717-5c43324-NIGHTLY/hello-world-fastopt/main.mjs:818:27)
    at $s_LMain__main__AT__V (file:///project/target/scala-3.2.1-RC1-bin-20220717-5c43324-NIGHTLY/hello-world-fastopt/main.mjs:804:15)
    at file:///project/target/scala-3.2.1-RC1-bin-20220717-5c43324-NIGHTLY/hello-world-fastopt/main.mjs:1744:1
    at ModuleJob.run (node:internal/modules/esm/module_job:198:25)
    at async Promise.all (index 0)
    at async ESMLoader.import (node:internal/modules/esm/loader:385:24)
    at async importModuleDynamicallyWrapper (node:internal/vm/module:437:15) {
  jl_Throwable__f_s: 'stub',
  jl_Throwable__f_e: null,
  jl_Throwable__f_enableSuppression: true,
  jl_Throwable__f_writableStackTrace: true,
  jl_Throwable__f_stackTraceStateInternal: [Circular *1],
  jl_Throwable__f_stackTrace: null,
  jl_Throwable__f_suppressed: null
}

Scala.JS on Scala 3 emits the line:

• fastLinkJS: throw $ct_jl_Error__T__(new $c_jl_Error(), "stub")
• fullLinkJS: throw new $c_jl_Error("stub")

On 2.13.8 the import is emitted as expected.

Expectation

Code runs without error and prints the expected message to the console. sbt ++2.13.x run works as expected, while sbt run gives the error above

[sjrd]

Yeah, I don't think we've implemented js.dynamicImport in Scala 3 yet. 😳