I noticed that sometimes we could get `NoSymbol` (I'm not saying the problem didn't exist before, I just noticed it now). I didn't see any visible bad effects, though.

```
Exception in thread "Text Viewer Hover Presenter" scala.reflect.internal.FatalError: no-symbol does not have an owner
	at scala.reflect.internal.SymbolTable.abort(SymbolTable.scala:53)
	at scala.tools.nsc.Global.abort(Global.scala:254)
	at scala.reflect.internal.Symbols$NoSymbol.owner(Symbols.scala:3355)
	at scala.tools.eclipse.LocateSymbol$class.findPath$1(LocateSymbol.scala:68)
	at scala.tools.eclipse.LocateSymbol$class.findSourceFile$1(LocateSymbol.scala:83)
	at scala.tools.eclipse.LocateSymbol$class.findCompilationUnit(LocateSymbol.scala:85)
	at scala.tools.eclipse.ScalaPresentationCompiler.findCompilationUnit(ScalaPresentationCompiler.scala:41)
	at scala.tools.eclipse.Scaladoc$class.parsedDocComment(Scaladoc.scala:51)
	at scala.tools.eclipse.ScalaPresentationCompiler.parsedDocComment(ScalaPresentationCompiler.scala:41)
	at scala.tools.eclipse.Scaladoc$class.browserInput(Scaladoc.scala:84)
	at scala.tools.eclipse.ScalaPresentationCompiler.browserInput(ScalaPresentationCompiler.scala:41)
	at scala.tools.eclipse.ScalaHover$$anonfun$getHoverInfo2$1$$anonfun$scala$tools$eclipse$ScalaHover$$anonfun$$hoverInfo$1$2.apply(ScalaHover.scala:62)
	at scala.tools.eclipse.ScalaHover$$anonfun$getHoverInfo2$1$$anonfun$scala$tools$eclipse$ScalaHover$$anonfun$$hoverInfo$1$2.apply(ScalaHover.scala:61)
	at scala.Option$WithFilter.map(Option.scala:206)
	at scala.tools.eclipse.ScalaHover$$anonfun$getHoverInfo2$1.scala$tools$eclipse$ScalaHover$$anonfun$$hoverInfo$1(ScalaHover.scala:61)
	at scala.tools.eclipse.ScalaHover$$anonfun$getHoverInfo2$1$$anonfun$apply$4.apply(ScalaHover.scala:75)
	at scala.tools.eclipse.ScalaHover$$anonfun$getHoverInfo2$1$$anonfun$apply$4.apply(ScalaHover.scala:75)
	at scala.Option.flatMap(Option.scala:170)
	at scala.tools.eclipse.ScalaHover$$anonfun$getHoverInfo2$1.apply(ScalaHover.scala:75)
	at scala.tools.eclipse.ScalaHover$$anonfun$getHoverInfo2$1.apply(ScalaHover.scala:30)
	at scala.tools.eclipse.ScalaPresentationCompiler.withSourceFile(ScalaPresentationCompiler.scala:117)
	at scala.tools.eclipse.ScalaProject$$anonfun$withSourceFile$1.apply(ScalaProject.scala:615)
	at scala.tools.eclipse.ScalaProject$$anonfun$withSourceFile$1.apply(ScalaProject.scala:614)
	at scala.tools.eclipse.ScalaProject$$anonfun$withPresentationCompiler$1.apply(ScalaProject.scala:608)
	at scala.tools.eclipse.ScalaProject$$anonfun$withPresentationCompiler$1.apply(ScalaProject.scala:607)
	at scala.tools.eclipse.util.Cached$class.apply(Cached.scala:41)
	at scala.tools.eclipse.ScalaProject$$anon$1.apply(ScalaProject.scala:113)
	at scala.tools.eclipse.ScalaProject.withPresentationCompiler(ScalaProject.scala:607)
	at scala.tools.eclipse.ScalaProject.withSourceFile(ScalaProject.scala:616)
	at scala.tools.eclipse.InteractiveCompilationUnit$class.withSourceFile(InteractiveCompilationUnit.scala:66)
	at scala.tools.eclipse.javaelements.ScalaSourceFile.withSourceFile(ScalaSourceFile.scala:60)
	at scala.tools.eclipse.ScalaHover.getHoverInfo2(ScalaHover.scala:76)
	at org.eclipse.jface.text.TextViewerHoverManager$4.run(TextViewerHoverManager.java:166)
```