Unable to `modify` nested case class

Given the following simple example:

package diffxsandbox
import com.softwaremill.diffx.generic.auto._
import com.softwaremill.diffx.Diff

case class Address(house: Int, street: String)
case class Person(name: String, address: Address) {
  def diff(other: Person) = {
    val add = Diff.summon[Address]

    val d = 
      Diff.summon[Person]
        .modify(_.address)
        .setTo(add)

    d.apply(this, other)
  }
}

object diffxdemo extends App {
  val a1 = Address(123, "Robin St.")
  val a2 = Address(456, "Robin St.")
  val p1 = Person("Mason", a1)
  val p2 = Person("Mason", a2)

  println {
    p1.diff(p2).isIdentical
  }
}

we are receiving the following stack trace

error] java.lang.ClassCastException: class java.lang.Integer cannot be cast to class scala.Product (java.lang.Integer is in module java.base of loader 'bootstrap'; scala.Product is in unnamed module of loader sbt.internal.ScalaLibraryClassLoader @616527ba)
[error]         at magnolia1.ReadOnlyParam$$anon$3.dereference(interface.scala:213)
[error]         at com.softwaremill.diffx.generic.DiffMagnoliaDerivation.$anonfun$join$3(DiffMagnoliaDerivation.scala:19)
[error]         at scala.collection.immutable.ArraySeq.map(ArraySeq.scala:75)
[error]         at scala.collection.immutable.ArraySeq.map(ArraySeq.scala:35)
[error]         at com.softwaremill.diffx.generic.DiffMagnoliaDerivation.$anonfun$join$2(DiffMagnoliaDerivation.scala:14)
[error]         at com.softwaremill.diffx.DiffxSupport.nullGuard(DiffxSupport.scala:20)
[error]         at com.softwaremill.diffx.DiffxSupport.nullGuard$(DiffxSupport.scala:14)
<elided...>

Does diffx support modification of nested case class parameters? If I instead provide Diff.useEquals[Address] instead of the automically derived instance, the example runs successfully.

[ghostbuster91]

We clearly miss some test cases for those. Thanks I will look into that.

[ghostbuster91]

I released another fix as 0.8.2 It should solve your problem but that is not a complete solution to that issue as there are still some edge cases where it will not work. I have an idea how to fix it completely but I need to rethink how to approach it.