I was unable to reproduce the issue, in my current codebase.
It seems that it happens because SmallestModules splits up a lot of the standard scala/java library, and the issue disappears once most of it ends up in java.lang.Object.js.
The error is I get is ReferenceError: $j_java$002elang$002eClass is not defined, and it seems to be resolved, when removing the Class Component, I'm guessing the Class Component takes in some Java/Scala code, that ends up calling the standard library, and it then fails because of odd linking issues with SmallestModules.
You need to:
-
Install the javascript libraries:
npm install
-
Create the bundle (in a separate terminal):
sbt
> ~fastLinkJS
or just
> fastLinkJS
-
Run Next.js dev server:
npm run dev
or
npm run build
The issue disappears if you delete the file HomeComponent or if you compile the Scala.js code with fullLinkJS (you might have to restart the dev server), also remember to clean before building, since the project uses the same output directory for fastLinkJS and fullLinkJS.