enum List.Nil compile error: Values of types List[Nothing] and MyList[Int] cannot be compared with == or !=

[maudslice]

Hello, When I try to copy the fpinscala code into my project, my IDE shows some compile errors, like the title, When the List.Nil appears to the left of a case statement in a pattern match, the compiler tells me that Values of types MyList[Nothing] and MyList[Int] cannot be compared with == or !=

  val factorialREPL: IO[Unit] = sequence_(
    PrintLine(helpstring),
    ReadLine.doWhile: line =>
      val ok = line != "q"
      when(ok):
        for
          n <- factorial(line.toInt)
          _ <- PrintLine("factorial: " + n)
        yield ()
  )

this code IDE show 4 error: Not found: type line; an identifier expected, but 'val' found; Not found: ok; an identifier expected, but 'for' found.
but when I pull down the whole project, the errors are compilable, I'm very puzzled, and I'd really like to get your help and advice!

[maudslice]

my env:
scalaVersion: 3.2.1
jdk: 17
build tool: sbt
IDE: IntelliJ IDEA 2023