Compile both files together first, then compiler just MyScanner.scala (don't need to be in resident mode), trans\
cript as follows:

bash-3.00$ scalac -d ../bin -sourcepath . test/*.scala
bash-3.00$ scalac -d ../bin -sourcepath . test/MyScanner.scala 
exception when traversing java.lang.Object with test.NodeImpl$class {
  private   val $outer : test.MyScannerTest = _;
     def $outer(): MyScannerTest.this.type = $anon$0.this.$outer ;
  def this($outer: test.MyScannerTest): $anon$0 = {
    if ($outer.eq(null))
      throw new java.lang.NullPointerException.this()
    else
      $anon$0.this.$outer  = $outer;
    {
      $anon$0.super.this();
      ()
    };
    $anon$0.this./*NodeImpl$class*/$init$($outer);
    $anon$0.this./*NodeImpl$class*/$init$($outer);
    ()
  }
}
exception when traversing final  class $anon$0 extends java.lang.Object with test.NodeImpl$class {
  private   val $outer : test.MyScannerTest = _;
     def $outer(): MyScannerTest.this.type = $anon$0.this.$outer ;
  def this($outer: test.MyScannerTest): $anon$0 = {
    if ($outer.eq(null))
      throw new java.lang.NullPointerException.this()
    else
      $anon$0.this.$outer  = $outer;
    {
      $anon$0.super.this();
      ()
    };
    $anon$0.this./*NodeImpl$class*/$init$($outer);
    $anon$0.this./*NodeImpl$class*/$init$($outer);
    ()
  }
}
exception when traversing package test {
  class MyScannerTest extends test.MyLinkedList with test.MyOffsetList with scala.ScalaObject {
    def init(): java.lang.Object with MyScannerTest.this.NodeImpl = {
      new test.$anon$0.this(MyScannerTest.this)
    };
     def init(): test.MyLinkedList#NodeImpl = MyScannerTest.this.init().$asInstanceOf[test.NodeImpl]();
\

    def this(): test.MyScannerTest = {
      {
        MyScannerTest.super.this();
        ()
      };
      MyScannerTest.this./*MyOffsetList$class*/$init$();
      ()
    }
  };
  final  class $anon$0 extends java.lang.Object with test.NodeImpl$class {
    private   val $outer : test.MyScannerTest = _;
       def $outer(): MyScannerTest.this.type = $anon$0.this.$outer ;
    def this($outer: test.MyScannerTest): $anon$0 = {
      if ($outer.eq(null))
        throw new java.lang.NullPointerException.this()
      else
        $anon$0.this.$outer  = $outer;
      {
        $anon$0.super.this();
        ()
      };
      $anon$0.this./*NodeImpl$class*/$init$($outer);
      $anon$0.this./*NodeImpl$class*/$init$($outer);
      ()
    }
  }
}
Exception in thread "main" java.lang.Error: assertion failed
	at scala.Predef$.assert(Predef.scala:170)
	at scala.tools.nsc.symtab.Types$Type.memberType(Types.scala:209)
	at scala.tools.nsc.symtab.Symbols$Symbol$$anonfun$6.apply(Symbols.scala:628)
	at scala.tools.nsc.symtab.Symbols$Symbol$$anonfun$6.apply(Symbols.scala:627)
	at scala.List.filter(List.scala:695)
	at scala.tools.nsc.symtab.Symbols$Symbol.filter(Symbols.scala:501)
	at scala.tools.nsc.symtab.Symbols$Symbol.matchingSymbol(Symbols.scala:627)
	at scala.tools.nsc.symtab.Symbols$Symbol.overridingSymbol(Symbols.scala:636)
	at scala.tools.nsc.transform.Mixin$$anonfun$2.apply(Mixin.scala:52)
	at scala.tools.nsc.transform.Mixin$$anonfun$2.apply(Mixin.scala:42)
	at scala.tools.nsc.symtab.SymbolTable.atPhase(SymbolTable.scala:41)
	at scala.tools.nsc.transform.Mixin.scala$tools$nsc$transform$Mixin$$rebindSuper(Mixin.scala:42)
	at scala.tools.nsc.transform.Mixin$$anonfun$9.apply(Mixin.scala:149)
	at scala.tools.nsc.transform.Mixin$$anonfun$9.apply(Mixin.scala:129)
	at scala.List.foreach(List.scala:681)
	at scala.tools.nsc.transform.Mixin.mixinMembers$0(Mixin.scala:129)
	at scala.tools.nsc.transform.Mixin$$anonfun$10.apply(Mixin.scala:160)
	at scala.tools.nsc.transform.Mixin$$anonfun$10.apply(Mixin.scala:160)
	at scala.List.foreach(List.scala:681)
	at scala.tools.nsc.transform.Mixin.addMixedinMembers(Mixin.scala:160)
	at scala.tools.nsc.transform.Mixin$MixinTransformer.preTransform(Mixin.scala:219)
	at scala.tools.nsc.transform.Mixin$MixinTransformer.transform(Mixin.scala:406)
	at scala.tools.nsc.ast.Trees$Transformer.transformTemplate(Trees.scala:1024)
	at scala.tools.nsc.ast.Trees$Transformer$$anonfun$13.apply(Trees.scala:930)
	at scala.tools.nsc.ast.Trees$Transformer$$anonfun$13.apply(Trees.scala:930)
	at scala.tools.nsc.ast.Trees$Transformer.atOwner(Trees.scala:1044)
	at scala.tools.nsc.ast.Trees$Transformer.transform(Trees.scala:929)
	at scala.tools.nsc.transform.Mixin$MixinTransformer.transform(Mixin.scala:406)
	at scala.tools.nsc.ast.Trees$Transformer$$anonfun$25.apply(Trees.scala:1038)
	at scala.tools.nsc.ast.Trees$Transformer$$anonfun$25.apply(Trees.scala:1036)
	at scala.List$.loop$0(List.scala:232)
	at scala.List$.mapConserve(List.scala:249)
	at scala.List$.loop$0(List.scala:236)
	at scala.List$.mapConserve(List.scala:249)
	at scala.tools.nsc.ast.Trees$Transformer.transformStats(Trees.scala:1036)
	at scala.tools.nsc.ast.Trees$Transformer$$anonfun$12.apply(Trees.scala:926)
	at scala.tools.nsc.ast.Trees$Transformer$$anonfun$12.apply(Trees.scala:926)
	at scala.tools.nsc.ast.Trees$Transformer.atOwner(Trees.scala:1044)
	at scala.tools.nsc.ast.Trees$Transformer.transform(Trees.scala:925)
	at scala.tools.nsc.transform.Mixin$MixinTransformer.transform(Mixin.scala:406)
	at scala.tools.nsc.ast.Trees$Transformer.transformUnit(Trees.scala:1039)
	at scala.tools.nsc.transform.Transform$Phase.apply(Transform.scala:22)
	at scala.tools.nsc.Global$GlobalPhase.applyPhase(Global.scala:214)
	at scala.tools.nsc.Global$GlobalPhase$$anonfun$1.apply(Global.scala:203)
	at scala.tools.nsc.Global$GlobalPhase$$anonfun$1.apply(Global.scala:203)
	at scala.Iterator$class.foreach(Iterator.scala:304)
	at scala.collection.mutable.ListBuffer$$anon$0.foreach(ListBuffer.scala:216)
	at scala.tools.nsc.Global$GlobalPhase.run(Global.scala:203)
	at scala.tools.nsc.Global$Run.compileSources(Global.scala:450)
	at scala.tools.nsc.Global$Run.compile(Global.scala:508)
	at scala.tools.nsc.Main$.process(Main.scala:60)
	at scala.tools.nsc.Main$.main(Main.scala:82)
	at scala.tools.nsc.Main.main(Main.scala)



Problem seems to be in the two methods both having the same name insertAfter, if we rename one method, the bug g\
oes away. Actually, its even stranger, if we don't instantiate Node, the bug also goes away. And if we don't ove\
rride insertAfter, the bug also goes away.