Unexpected empty value when accessing object val

[Sporarum]

Compiler version

3.1.3
Rest of scastie settings:

scalacOptions ++= Seq(
  "-deprecation",
  "-encoding", "UTF-8",
  "-feature",
  "-unchecked",
  "-Yexplicit-nulls" // not necessary, but worrying that it works even with it
)

scalaVersion := "3.1.3"
libraryDependencies += "org.scastie" %% "runtime-scala" % "1.0.0-SNAPSHOT"

addSbtPlugin("org.scastie" % "sbt-scastie" % "1.0.0-SNAPSHOT")

Minimized code

object A:
  val a = B.seed

object B:
  val seed = (0,0) // 'c' // 1 // "test"
  val b = A.a

A.a // remove and it works as expected
B.b

https://scastie.scala-lang.org/Sporarum/KrfWCxvTQfqrb7dMoi9NqA/69

Output

A.a => "(0,0): scala.Tuple2[scala.Int, scala.Int]" // "c: scala.Char" // "1: scala.Int" // "test: scala.String"
B.b => "null: scala.Tuple2[scala.Int, scala.Int]"  // ": scala.Char"  // "0: scala.Int" // "null: scala.String"

It is also possible to append B.b._1 to get a NullPointerException in the case where seed is a tuple
Note that this is the case even with -Yexplicit-nulls !

If the call to A.a is removed, or if seed is an inline val (or def in the case of (0,0)):

B.b => "(0,0): scala.Tuple2[scala.Int, scala.Int]" // "c: scala.Char" // "1: scala.Int" // "test: scala.String"

Expectation

The inclusion/removal of the A.a call should not affect the value of B.b !
If those kinds of references are forbidden, an error should be issued

[odersky]

I believe that's just a shortcoming of how objects are initialized on the JVM. Mutually recursive references between static objects can give nulls.