Malformed code leads to compiler crash

[scabug]

The following line leads to to a compiler crash:

def v = new ({ def a=0 })

results in:

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scala> def v = new ({ def a=0 })
<console>:5: error: class type required but AnyRef{def a: <?>} found
       def v = new ({ def a=0 })
                    ^
Exception in thread "main" scala.tools.nsc.symtab.Types$$TypeError: only declarations allowed here
        at scala.tools.nsc.typechecker.Contexts$$Context.error(Contexts.scala:273)
        at scala.tools.nsc.typechecker.Infer$$Inferencer.error(Infer.scala:213)
        at scala.tools.nsc.typechecker.Infer$$Inferencer.errorTree(Infer.scala:217)
        at scala.tools.nsc.typechecker.Typers$$Typer.typedStat$$1(Typers.scala:2050)
        at scala.tools.nsc.typechecker.Typers$$Typer$$$$anonfun$$20.apply(Typers.scala:2135)
        at scala.tools.nsc.typechecker.Typers$$Typer$$$$anonfun$$20.apply(Typers.scala:2135)
        at scala.collection.immutable.List.loop$$1(List.scala:115)
        at scala.collection.immutable.List.mapConserve(List.scala:132)
        at scala.tools.nsc.typechecker.Typers$$Typer.typedStats(Typers.scala:2135)
        at scala.tools.nsc.typechecker.Typers$$Typer$$$$anonfun$$typedRefinement$$1.apply$$mcV$$sp(Typers.scala:2030)
        at scala.tools.nsc.typechecker.Analyzer$$typerFactory$$$$anon$$3$$$$anonfun$$apply$$1.apply(Analyzer.scala:87)
        at scala.tools.nsc.typechecker.Analyzer$$typerFactory$$$$anon$$3$$$$anonfun$$apply$$1.apply(Analyzer.scala:87)
        at scala.collection.LinearSeqOptimized$$class.foreach(LinearSeqOptimized.scala:61)
        at scala.collection.immutable.List.foreach(List.scala:45)
        at scala.collection.generic.TraversableForwarder$$class.foreach(TraversableForwarder.scala:44)
        at scala.collection.mutable.ListBuffer.foreach(ListBuffer.scala:42)
        at scala.tools.nsc.typechecker.Analyzer$$typerFactory$$$$anon$$3.apply(Analyzer.scala:87)
        at scala.tools.nsc.Global$$GlobalPhase$$$$anonfun$$applyPhase$$1.apply$$mcV$$sp(Global.scala:278)
        at scala.tools.nsc.Global$$GlobalPhase$$$$anonfun$$applyPhase$$1.apply(Global.scala:278)
        at scala.tools.nsc.Global$$GlobalPhase$$$$anonfun$$applyPhase$$1.apply(Global.scala:278)
        at scala.tools.nsc.reporters.Reporter.withSource(Reporter.scala:48)
        at scala.tools.nsc.Global$$GlobalPhase.applyPhase(Global.scala:278)
        at scala.tools.nsc.typechecker.Analyzer$$typerFactory$$$$anon$$3$$$$anonfun$$run$$1.apply(Analyzer.scala:80)
        at scala.tools.nsc.typechecker.Analyzer$$typerFactory$$$$anon$$3$$$$anonfun$$run$$1.apply(Analyzer.scala:80)
        at scala.collection.Iterator$$class.foreach(Iterator.scala:631)
        at scala.collection.mutable.ListBuffer$$$$anon$$1.foreach(ListBuffer.scala:304)
        at scala.tools.nsc.typechecker.Analyzer$$typerFactory$$$$anon$$3.run(Analyzer.scala:80)
        at scala.tools.nsc.Global$$Run.compileSources(Global.scala:735)

[scabug]

Imported From: https://issues.scala-lang.org/browse/SI-3614?orig=1
Reporter: @cunei

[scabug]

@odersky said:
(In r23285) Closes #3614. Closes #3856. Refined handling of imports to avoid trees with null types in presentation compiler. Review by moors