Dottydoc fails to read symbol in scalajs project on RC2

[error] -- Error: kernel/js/src/main/scala/cats/effect/kernel/AsyncPlatform.scala:38:8 -
[error] 38 |        p.`then`[Unit](onFulfilled, defined(onRejected))
[error]    |        ^^^^^^^^^^^^^
[error]    |undefined: p.then # -1: TermRef(TermRef(NoPrefix,val p),then) at readTasty

Not very minimized, sorry. Here is the exact line and commit hash: https://github.com/typelevel/cats-effect/blob/dedfedecf843e4272488eeaa71581d64eeb08194/kernel/js/src/main/scala/cats/effect/kernel/AsyncPlatform.scala#L38 This compiles and runs just fine on 2.12, 2.13, RC1, and RC2. However, when I attempt to run sbt doc, it errors here.

[VlachJosef]

Same problem is happening in https://github.com/playframework/play-json/pull/590

[error] -- Error: play-json/js/src/main/scala/StaticBinding.scala:118:25 --------------------------------------------------------------------------------------------
[error] 118 |    if (!escapeNonASCII) JSON.stringify(s) else escapeStr(JSON.stringify(s))
[error]     |                         ^^^^^^^^^^^^^^^^
[error]     |undefined: scala.scalajs.js.JSON.stringify # -1: TermRef(TermRef(TermRef(ThisType(TypeRef(NoPrefix,module class scalajs)),object js),JSON),stringify) at readTasty
...
[error] (play-jsonJS / Compile / doc) DottyDoc Compilation Failed

Workaround there was to provide missing argument for JSON.stringify(s, null)

[griggt]

Without cats-effect:

import scala.scalajs.js.{|, defined, Function1, Promise, Thenable}

trait Foo {
  def bar[A](p: Promise[A]) = {
    val onFulfilled: Function1[A, Unit | Thenable[Unit]] = ???
    val onRejected: Function1[Any, Unit | Thenable[Unit]] = ???
    p.`then`[Unit](onFulfilled, defined(onRejected))
  }
}

Seems to have been working before #11671