java.lang.AssertionError: assertion failed: <MyTrait: error>.this
    at scala.reflect.internal.Trees$SelectFromTypeTree.<init>(Trees.scala:568)
    at scala.reflect.internal.Trees$StrictTreeCopier.SelectFromTypeTree(Trees.scala:738)
    at scala.reflect.internal.Trees$StrictTreeCopier.SelectFromTypeTree(Trees.scala:652)
    at scala.reflect.internal.Trees$LazyTreeCopier.SelectFromTypeTree(Trees.scala:949)
    at scala.reflect.internal.Trees$LazyTreeCopier.SelectFromTypeTree(Trees.scala:749)
    at scala.tools.nsc.typechecker.Typers$Typer.typedSelectInternal$1(Typers.scala:4667)
    at scala.tools.nsc.typechecker.Typers$Typer.scala$tools$nsc$typechecker$Typers$Typer$$typedSelect$1(Typers.scala:4594)
    at scala.tools.nsc.typechecker.Typers$Typer.typedSelectFromTypeTree$1(Typers.scala:5153)
    at scala.tools.nsc.typechecker.Typers$Typer.typedTypTree$1(Typers.scala:5206)
    at scala.tools.nsc.typechecker.Typers$Typer.typed1(Typers.scala:5264)
    at scala.tools.nsc.typechecker.Typers$Typer.runTyper$1(Typers.scala:5303)
    at scala.tools.nsc.typechecker.Typers$Typer.scala$tools$nsc$typechecker$Typers$Typer$$typedInternal(Typers.scala:5330)
    at scala.tools.nsc.typechecker.Typers$Typer.body$2(Typers.scala:5277)
    at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:5281)
    at scala.tools.nsc.interpreter.ReplGlobal$$anon$1$$anon$2.typed(ReplGlobal.scala:36)
    at scala.tools.nsc.typechecker.Typers$Typer.typedType(Typers.scala:5424)
    at scala.tools.nsc.typechecker.Typers$Typer.typedType(Typers.scala:5427)
    at scala.tools.nsc.typechecker.Namers$Namer.valDefSig(Namers.scala:1378)
    at scala.tools.nsc.typechecker.Namers$Namer.getSig$1(Namers.scala:1528)
    at scala.tools.nsc.typechecker.Namers$Namer.typeSig(Namers.scala:1537)
    at scala.tools.nsc.typechecker.Namers$Namer$$anonfun$monoTypeCompleter$1$$anonfun$apply$1.apply$mcV$sp(Namers.scala:781)
    at scala.tools.nsc.typechecker.Namers$Namer$$anonfun$monoTypeCompleter$1$$anonfun$apply$1.apply(Namers.scala:780)
    at scala.tools.nsc.typechecker.Namers$Namer$$anonfun$monoTypeCompleter$1$$anonfun$apply$1.apply(Namers.scala:780)
    at scala.tools.nsc.typechecker.Namers$Namer.scala$tools$nsc$typechecker$Namers$Namer$$logAndValidate(Namers.scala:1564)
    at scala.tools.nsc.typechecker.Namers$Namer$$anonfun$monoTypeCompleter$1.apply(Namers.scala:780)
    at scala.tools.nsc.typechecker.Namers$Namer$$anonfun$monoTypeCompleter$1.apply(Namers.scala:772)
    at scala.tools.nsc.typechecker.Namers$$anon$1.completeImpl(Namers.scala:1679)
    at scala.tools.nsc.typechecker.Namers$LockingTypeCompleter$class.complete(Namers.scala:1687)
    at scala.tools.nsc.typechecker.Namers$$anon$1.complete(Namers.scala:1677)
    at scala.reflect.internal.Symbols$Symbol.info(Symbols.scala:1429)
    at scala.tools.nsc.typechecker.Namers$DependentTypeChecker.check(Namers.scala:1747)
    at scala.tools.nsc.typechecker.Namers$Namer.thisMethodType$1(Namers.scala:1047)
    at scala.tools.nsc.typechecker.Namers$Namer.methodSig(Namers.scala:1198)
    at scala.tools.nsc.typechecker.Namers$Namer.getSig$1(Namers.scala:1525)
    at scala.tools.nsc.typechecker.Namers$Namer.typeSig(Namers.scala:1537)
    at scala.tools.nsc.typechecker.Namers$Namer$$anonfun$monoTypeCompleter$1$$anonfun$apply$1.apply$mcV$sp(Namers.scala:781)
    at scala.tools.nsc.typechecker.Namers$Namer$$anonfun$monoTypeCompleter$1$$anonfun$apply$1.apply(Namers.scala:780)
    at scala.tools.nsc.typechecker.Namers$Namer$$anonfun$monoTypeCompleter$1$$anonfun$apply$1.apply(Namers.scala:780)
    at scala.tools.nsc.typechecker.Namers$Namer.scala$tools$nsc$typechecker$Namers$Namer$$logAndValidate(Namers.scala:1564)
    at scala.tools.nsc.typechecker.Namers$Namer$$anonfun$monoTypeCompleter$1.apply(Namers.scala:780)
    at scala.tools.nsc.typechecker.Namers$Namer$$anonfun$monoTypeCompleter$1.apply(Namers.scala:772)
    at scala.tools.nsc.typechecker.Namers$$anon$1.completeImpl(Namers.scala:1679)
    at scala.tools.nsc.typechecker.Namers$LockingTypeCompleter$class.complete(Namers.scala:1687)
    at scala.tools.nsc.typechecker.Namers$$anon$1.complete(Namers.scala:1677)
    at scala.reflect.internal.Symbols$Symbol.info(Symbols.scala:1429)
    at scala.reflect.internal.Symbols$Symbol.initialize(Symbols.scala:1576)
    at scala.tools.nsc.typechecker.Typers$Typer.typed1(Typers.scala:4919)
    at scala.tools.nsc.typechecker.Typers$Typer.runTyper$1(Typers.scala:5303)
    at scala.tools.nsc.typechecker.Typers$Typer.scala$tools$nsc$typechecker$Typers$Typer$$typedInternal(Typers.scala:5330)
    at scala.tools.nsc.typechecker.Typers$Typer.body$2(Typers.scala:5277)
    at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:5281)
    at scala.tools.nsc.interpreter.ReplGlobal$$anon$1$$anon$2.typed(ReplGlobal.scala:36)
    at scala.tools.nsc.typechecker.Typers$Typer.typedByValueExpr(Typers.scala:5359)
    at scala.tools.nsc.typechecker.Typers$Typer.scala$tools$nsc$typechecker$Typers$Typer$$typedStat$1(Typers.scala:2998)
    at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$62.apply(Typers.scala:3102)
    at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$62.apply(Typers.scala:3102)
    at scala.collection.immutable.List.loop$1(List.scala:172)
    at scala.collection.immutable.List.mapConserve(List.scala:188)
    at scala.tools.nsc.typechecker.Typers$Typer.typedStats(Typers.scala:3102)
    at scala.tools.nsc.typechecker.Typers$Typer.typedTemplate(Typers.scala:1904)
    at scala.tools.nsc.typechecker.Typers$Typer.typedClassDef(Typers.scala:1750)
    at scala.tools.nsc.typechecker.Typers$Typer.typedMemberDef$1(Typers.scala:5216)
    at scala.tools.nsc.typechecker.Typers$Typer.typed1(Typers.scala:5266)
    at scala.tools.nsc.typechecker.Typers$Typer.runTyper$1(Typers.scala:5303)
    at scala.tools.nsc.typechecker.Typers$Typer.scala$tools$nsc$typechecker$Typers$Typer$$typedInternal(Typers.scala:5330)
    at scala.tools.nsc.typechecker.Typers$Typer.body$2(Typers.scala:5277)
    at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:5281)
    at scala.tools.nsc.interpreter.ReplGlobal$$anon$1$$anon$2.typed(ReplGlobal.scala:36)
    at scala.tools.nsc.typechecker.Typers$Typer.typedByValueExpr(Typers.scala:5359)
    at scala.tools.nsc.typechecker.Typers$Typer.scala$tools$nsc$typechecker$Typers$Typer$$typedStat$1(Typers.scala:2998)
    at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$62.apply(Typers.scala:3102)
    at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$62.apply(Typers.scala:3102)
    at scala.collection.immutable.List.loop$1(List.scala:172)
    at scala.collection.immutable.List.mapConserve(List.scala:188)
    at scala.tools.nsc.typechecker.Typers$Typer.typedStats(Typers.scala:3102)
    at scala.tools.nsc.typechecker.Typers$Typer.typedTemplate(Typers.scala:1904)
    at scala.tools.nsc.typechecker.Typers$Typer.typedModuleDef(Typers.scala:1791)
    at scala.tools.nsc.typechecker.Typers$Typer.typedMemberDef$1(Typers.scala:5217)
    at scala.tools.nsc.typechecker.Typers$Typer.typed1(Typers.scala:5266)
    at scala.tools.nsc.typechecker.Typers$Typer.runTyper$1(Typers.scala:5303)
    at scala.tools.nsc.typechecker.Typers$Typer.scala$tools$nsc$typechecker$Typers$Typer$$typedInternal(Typers.scala:5330)
    at scala.tools.nsc.typechecker.Typers$Typer.body$2(Typers.scala:5277)
    at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:5281)
    at scala.tools.nsc.interpreter.ReplGlobal$$anon$1$$anon$2.typed(ReplGlobal.scala:36)
    at scala.tools.nsc.typechecker.Typers$Typer.typedByValueExpr(Typers.scala:5359)
    at scala.tools.nsc.typechecker.Typers$Typer.scala$tools$nsc$typechecker$Typers$Typer$$typedStat$1(Typers.scala:2998)
    at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$62.apply(Typers.scala:3102)
    at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$62.apply(Typers.scala:3102)
    at scala.collection.immutable.List.loop$1(List.scala:172)
    at scala.collection.immutable.List.mapConserve(List.scala:188)
    at scala.tools.nsc.typechecker.Typers$Typer.typedStats(Typers.scala:3102)
    at scala.tools.nsc.typechecker.Typers$Typer.typedTemplate(Typers.scala:1904)
    at scala.tools.nsc.typechecker.Typers$Typer.typedModuleDef(Typers.scala:1791)
    at scala.tools.nsc.typechecker.Typers$Typer.typedMemberDef$1(Typers.scala:5217)
    at scala.tools.nsc.typechecker.Typers$Typer.typed1(Typers.scala:5266)
    at scala.tools.nsc.typechecker.Typers$Typer.runTyper$1(Typers.scala:5303)
    at scala.tools.nsc.typechecker.Typers$Typer.scala$tools$nsc$typechecker$Typers$Typer$$typedInternal(Typers.scala:5330)
    at scala.tools.nsc.typechecker.Typers$Typer.body$2(Typers.scala:5277)
    at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:5281)
    at scala.tools.nsc.interpreter.ReplGlobal$$anon$1$$anon$2.typed(ReplGlobal.scala:36)
    at scala.tools.nsc.typechecker.Typers$Typer.typedByValueExpr(Typers.scala:5359)
    at scala.tools.nsc.typechecker.Typers$Typer.scala$tools$nsc$typechecker$Typers$Typer$$typedStat$1(Typers.scala:2998)
    at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$62.apply(Typers.scala:3102)
    at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$62.apply(Typers.scala:3102)
    at scala.collection.immutable.List.loop$1(List.scala:172)
    at scala.collection.immutable.List.mapConserve(List.scala:188)
    at scala.tools.nsc.typechecker.Typers$Typer.typedStats(Typers.scala:3102)
    at scala.tools.nsc.typechecker.Typers$Typer.typedTemplate(Typers.scala:1904)
    at scala.tools.nsc.typechecker.Typers$Typer.typedModuleDef(Typers.scala:1791)
    at scala.tools.nsc.typechecker.Typers$Typer.typedMemberDef$1(Typers.scala:5217)
    at scala.tools.nsc.typechecker.Typers$Typer.typed1(Typers.scala:5266)
    at scala.tools.nsc.typechecker.Typers$Typer.runTyper$1(Typers.scala:5303)
    at scala.tools.nsc.typechecker.Typers$Typer.scala$tools$nsc$typechecker$Typers$Typer$$typedInternal(Typers.scala:5330)
    at scala.tools.nsc.typechecker.Typers$Typer.body$2(Typers.scala:5277)
    at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:5281)
    at scala.tools.nsc.interpreter.ReplGlobal$$anon$1$$anon$2.typed(ReplGlobal.scala:36)
    at scala.tools.nsc.typechecker.Typers$Typer.typedByValueExpr(Typers.scala:5359)
    at scala.tools.nsc.typechecker.Typers$Typer.scala$tools$nsc$typechecker$Typers$Typer$$typedStat$1(Typers.scala:2998)
    at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$62.apply(Typers.scala:3102)
    at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$62.apply(Typers.scala:3102)
    at scala.collection.immutable.List.loop$1(List.scala:172)
    at scala.collection.immutable.List.mapConserve(List.scala:188)
    at scala.tools.nsc.typechecker.Typers$Typer.typedStats(Typers.scala:3102)
    at scala.tools.nsc.typechecker.Typers$Typer.typedPackageDef$1(Typers.scala:4926)
    at scala.tools.nsc.typechecker.Typers$Typer.typedMemberDef$1(Typers.scala:5219)
    at scala.tools.nsc.typechecker.Typers$Typer.typed1(Typers.scala:5266)
    at scala.tools.nsc.typechecker.Typers$Typer.runTyper$1(Typers.scala:5303)
    at scala.tools.nsc.typechecker.Typers$Typer.scala$tools$nsc$typechecker$Typers$Typer$$typedInternal(Typers.scala:5330)
    at scala.tools.nsc.typechecker.Typers$Typer.body$2(Typers.scala:5277)
    at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:5281)
    at scala.tools.nsc.interpreter.ReplGlobal$$anon$1$$anon$2.typed(ReplGlobal.scala:36)
    at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:5355)
    at scala.tools.nsc.typechecker.Analyzer$typerFactory$$anon$3.apply(Analyzer.scala:102)
    at scala.tools.nsc.Global$GlobalPhase.applyPhase(Global.scala:430)
    at scala.tools.nsc.typechecker.Analyzer$typerFactory$$anon$3$$anonfun$run$1.apply(Analyzer.scala:94)
    at scala.tools.nsc.typechecker.Analyzer$typerFactory$$anon$3$$anonfun$run$1.apply(Analyzer.scala:93)
    at scala.collection.Iterator$class.foreach(Iterator.scala:743)
    at scala.collection.AbstractIterator.foreach(Iterator.scala:1174)
    at scala.tools.nsc.typechecker.Analyzer$typerFactory$$anon$3.run(Analyzer.scala:93)
    at scala.tools.nsc.Global$Run.compileUnitsInternal(Global.scala:1625)
    at scala.tools.nsc.Global$Run.compileUnits(Global.scala:1610)
    at scala.tools.nsc.Global$Run.compileSources(Global.scala:1605)
    at scala.tools.nsc.interpreter.IMain.compileSourcesKeepingRun(IMain.scala:388)
    at scala.tools.nsc.interpreter.IMain$ReadEvalPrint.compileAndSaveRun(IMain.scala:804)
    at scala.tools.nsc.interpreter.IMain$ReadEvalPrint.compile(IMain.scala:763)
    at scala.tools.nsc.interpreter.IMain$Request.compile$lzycompute(IMain.scala:939)
    at scala.tools.nsc.interpreter.IMain$Request.compile(IMain.scala:934)
    at scala.tools.nsc.interpreter.IMain.compile(IMain.scala:531)
    at scala.tools.nsc.interpreter.IMain.interpret(IMain.scala:519)
    at scala.tools.nsc.interpreter.IMain.interpret(IMain.scala:517)
    at scala.tools.nsc.interpreter.ILoop.reallyInterpret$1(ILoop.scala:748)
    at scala.tools.nsc.interpreter.ILoop.interpretStartingWith(ILoop.scala:793)
    at scala.tools.nsc.interpreter.ILoop.command(ILoop.scala:660)
    at scala.tools.nsc.interpreter.ILoop.processLine(ILoop.scala:427)
    at scala.tools.nsc.interpreter.ILoop.loop(ILoop.scala:444)
    at scala.tools.nsc.interpreter.ILoop$$anonfun$process$1.apply$mcZ$sp(ILoop.scala:862)
    at scala.tools.nsc.interpreter.ILoop$$anonfun$process$1.apply(ILoop.scala:848)
    at scala.tools.nsc.interpreter.ILoop$$anonfun$process$1.apply(ILoop.scala:848)
    at scala.reflect.internal.util.ScalaClassLoader$.savingContextLoader(ScalaClassLoader.scala:95)
    at scala.tools.nsc.interpreter.ILoop.process(ILoop.scala:848)
    at scala.tools.nsc.interpreter.ILoop.main(ILoop.scala:870)
    at xsbt.ConsoleInterface.run(ConsoleInterface.scala:69)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:483)
    at sbt.compiler.AnalyzingCompiler.call(AnalyzingCompiler.scala:102)
    at sbt.compiler.AnalyzingCompiler.console(AnalyzingCompiler.scala:77)
    at sbt.Console.sbt$Console$$console0$1(Console.scala:23)
    at sbt.Console$$anonfun$apply$2$$anonfun$apply$1.apply$mcV$sp(Console.scala:24)
    at sbt.Console$$anonfun$apply$2$$anonfun$apply$1.apply(Console.scala:24)
    at sbt.Console$$anonfun$apply$2$$anonfun$apply$1.apply(Console.scala:24)
    at sbt.Logger$$anon$4.apply(Logger.scala:90)
    at sbt.TrapExit$App.run(TrapExit.scala:244)
    at java.lang.Thread.run(Thread.java:744)

That entry seems to have slain the compiler.  Shall I replay
your session? I can re-run each line except the last one.