Implicit lookup failing for Scala.js under Scala 3

[Rich2]

I originally posted a version of this suspected bug in the Scala.js issue tracker, but was told to repost it here. I have created a simplified repository of my main repository here. This repository is created from the openstrat. The code compiles for Jvm but is failing for Scala.js. There are 2 modules Util and Graphics. Util compiles under all 4 combinations of Js and Jvm targets and Scala 2.13.6 and Scala 3.0.1-RC2. The graphics module fails for Scala.js on Scala 3. In Sbt

graphicsJvm2/compile //compiles
graphicsJvm3/compile //compiles
graphicsJs2/compile //compiles
graphicsJs3/compile //gives the errors below

using Scala 2.13.6 and 3.0.1-RC2

The difference seems to be about implicit look up. If the 2 errors are eliminated, new implicit look up errors appear.

[info] compiling 177 Scala sources to /Common/jvmjs/graphicsJs3/target/scala-3.0.1-RC2/classes ...
[error] -- Error: /Common/jvmjs/srcGraphics/Trans/ProlignMatrix.scala:48:50 ------------
[error] 48 |    (arrA : Arr[A], prolignMatrix: ProlignMatrix) => arrA.map(a => ev.prolignObj(a, prolignMatrix))
[error]    |                                                                         ^ 
[error]    |bridge generated for member method prolignObj(arrA: ostrat.Arr[A], prolignMatrix: ostrat.geom.ProlignMatrix): ostrat.Arr[A] in anonymous class Object with ostrat.geom.Prolign {...}
[error]    |which overrides method prolignObj(obj: A, prolignMatrix: ostrat.geom.ProlignMatrix): A in trait Prolign
[error]    |clashes with definition of the member itself; both have erased type (arrA: Object, prolignMatrix: ostrat.geom.ProlignMatrix): Object."
[error] -- Error: /Common/jvmjs/srcGraphics/Trans/Slate.scala:28:84 --------------------
[error] 28 |  implicit def arrImplicit[A](implicit ev: Slate[A]): Slate[Arr[A]] = (obj, dx, dy) => obj.smap(ev.SlateXYT(_, dx, dy))
[error]    |                                                                                                                       ^
[error]    |bridge generated for member method SlateXYT(obj: ostrat.Arr[A], dx: Double, dy: Double): ostrat.Arr[A] in anonymous class Object with ostrat.geom.Slate {...}
[error]    |which overrides method SlateXYT(obj: T, xDelta: Double, yDelta: Double): T in trait Slate
[error]    |clashes with definition of the member itself; both have erased type (obj: Object, dx: Double, dy: Double): Object."

[error] two errors found
[error] two errors found
[error] (graphicsJs3 / Compile / compileIncremental) Compilation failed
[error] Total time: 3 s, completed 28 Jun 2021, 10:30:12

[dwijnand]

I originally posted a version of this suspected bug in the Scala.js issue tracker, but was told to repost it here.

Here's the issue: scala-js/scala-js#4486. As mentioned, Scala 3 bugs should be reported to https://github.com/lampepfl/dotty/issues.