Compiler crash in compileIncremental on Dotty project

[odersky]

Steps to reproduce:

• Start a fresh sbt on the Dotty project (with an empty classpath)
• clean
• ~compile
• Go to Config.scala and edit final val tracingEnabled = false to final val tracingEnabled = true

Here's the log I see:

1. Waiting for source changes in project dotty... (press enter to interrupt)
   [info] Compiling 1 Scala source to /Users/odersky/workspace/dotty/compiler/target/scala-0.14/classes ...
   [info] Done compiling.
   [info] Compiling 2 Scala sources to /Users/odersky/workspace/dotty/compiler/target/scala-0.14/classes ...
   [info] Done compiling.
   [info] Compiling 22 Scala sources to /Users/odersky/workspace/dotty/compiler/target/scala-0.14/classes ...
   dotty.tools.FatalError:
   at dotty.tools.dotc.typer.ErrorReporting$Errors.takesNoParamsStr(ErrorReporting.scala:84)
   at dotty.tools.dotc.typer.TypeAssigner.fail$2$$anonfun$1(TypeAssigner.scala:394)
   at dotty.tools.dotc.reporting.diagnostic.MessageContainer.contained(MessageContainer.scala:59)
   at dotty.tools.dotc.reporting.diagnostic.MessageContainer.message(MessageContainer.scala:42)
   at dotty.tools.dotc.reporting.diagnostic.MessageContainer.isNonSensical(MessageContainer.scala:71)
   at dotty.tools.dotc.reporting.HideNonSensicalMessages.isHidden(HideNonSensicalMessages.scala:17)
   at dotty.tools.dotc.reporting.AbstractReporter.isHidden(AbstractReporter.scala:8)
   at dotty.tools.dotc.reporting.Reporter.report(Reporter.scala:225)
   at dotty.tools.dotc.reporting.Reporting.error(Reporter.scala:105)
   at dotty.tools.dotc.core.Contexts$Context.error(Contexts.scala:71)
   at dotty.tools.dotc.typer.ErrorReporting$.errorType(ErrorReporting.scala:26)
   at dotty.tools.dotc.typer.TypeAssigner.fail$1(TypeAssigner.scala:394)
   at dotty.tools.dotc.typer.TypeAssigner.assignType(TypeAssigner.scala:460)
   at dotty.tools.dotc.typer.Typer.assignType(Typer.scala:87)
   at dotty.tools.dotc.ast.tpd$.TypeApply(tpd.scala:51)
   at dotty.tools.dotc.core.tasty.TreeUnpickler$TreeReader.readLengthTerm$1(TreeUnpickler.scala:1086)
   at dotty.tools.dotc.core.tasty.TreeUnpickler$TreeReader.readTerm(TreeUnpickler.scala:1203)
   at dotty.tools.dotc.core.tasty.TreeUnpickler$TreeReader.readLengthTerm$1(TreeUnpickler.scala:1083)
   at dotty.tools.dotc.core.tasty.TreeUnpickler$TreeReader.readTerm(TreeUnpickler.scala:1203)