usage of call.argument without any parameter leads to compiler error

cpg.call.codeExact("...").head match {
     case (call : nodes.Call) :: Nil =>
          println(call.argument.l.length)
}

leads to compiler error:

missing argument list for method argument in class CallMethods
[error] Unapplied methods are only converted to functions when a function type is expected.
[error] You can make this conversion explicit by writing `argument _` or `argument(_)` instead of `argument`.

When applying the suggested fix:

cpg.call.codeExact("...").head match {
     case (call : nodes.Call) :: Nil =>
          println(call.argument(_).l.length)
}

I get the compiler error:

missing parameter type for expanded function ((<x$1: error>) => call.argument(x$1).l.length.shouldBe(1))
[error]           println(call.argument(_).l.length)
[error]  

I was expecting to simply print the amount of arguments connected to that call node.

Current work-around:

cpg.call.codeExact("...").head match {
     case (call : nodes.Call) :: Nil =>
          println(call.out(EdgeTypes.ARGUMENT).asScala.toList.length)
}

I am using cpg version: 1.2.25

Reproduce the compiler error with the Scala snippet and inspect the CallMethods.argument API together with the shown EdgeTypes.ARGUMENT workaround. Confirm that the intended argument-count expression compiles and returns the same count without requiring an explicit parameter.