scaladoc 2.12.6 crash on @throws with -implicits

[hsn10]

It happens when i cross compile my getopt project to scala 2.12.6

Project URL: https://gitlab.com/hsn10/getopt
Reproducible at branch master: https://gitlab.com/hsn10/getopt/commits/master at revision https://gitlab.com/hsn10/getopt/tree/c41c3870b00e195848b2b351539c1150210af032

JDK: Oracle jdk1.8.0_162 64 bit
Steps to reproduce: sbt +doc
Workaround: comment -implicits scalac option to make it work

scalacOptions in (Compile,doc) := Seq("-groups", /* "-implicits", */"-no-link-warnings")

[error] (compile:doc) java.lang.AssertionError: assertion failed:
[error]
[error]      while compiling: C:\Users\hsn\Documents\scala\getopt\src\main\scala\package.scala
[error]         during phase: globalPhase=terminal, enteringPhase=typer
[error]      library version: version 2.12.6
[error]     compiler version: version 2.12.6
[error]   reconstructed args: -implicits -groups -bootclasspath C:\Program files\Java\jdk1.8.0_162\jre\lib\resources.jar;C:\Program files\Java\jdk1.8.0_162\jre\lib\rt.jar;C:\Program files\Java\jdk1.8.0_162\jre\lib\sunrsasign.jar;C:\Program files\Java\jdk1.8.0_162\jre\lib\jsse.jar;C:\Program files\Java\jdk1.8.0_162\jre\lib\jce.jar;C:\Program files\Java\jdk1.8.0_162\jre\lib\charsets.jar;C:\Program files\Java\jdk1.8.0_162\jre\lib\jfr.jar;C:\Program files\Java\jdk1.8.0_162\jre\classes;C:\Users\hsn\.ivy2\cache\org.scala-lang\scala-library\jars\scala-library-2.12.6.jar -d C:\Users\hsn\Documents\scala\getopt\target\scala-2.12\api -no-link-warnings -classpath dummy_28c0f775
[error]
[error]   last tree to typer: Ident(<argument>)
[error]        tree position: <unknown>
[error]             tree tpe: com.filez.scala.getopt.getopt
[error]               symbol: <none>
[error]    symbol definition: <none> (a NoSymbol)
[error]       symbol package: <none>
[error]        symbol owners:
[error]            call site: package <root> in <none>
[error]
[error] == Source file context for tree position ==

[xuwei-k]

minimized

build.sbt

scalacOptions in (Compile, doc) := Seq("-implicits")

scalaVersion := "2.12.6"

Foo.scala

package example

/**
 * @throws java.lang.IllegalArgumentException bar
 */
class Foo

execute sbt doc

[raboof]

(I can confirm this issue still occurs on 2.12.8 for a scaladoc annotation with a @throws on a class)