Do not nullify Modules

Author: HarrisL2

compiler/src/dotty/tools/dotc/core/JavaNullInterop.scala

@@ -58,8 +58,9 @@ object JavaNullInterop {
     // assert(sym.is(JavaDefined), "can only nullify java-defined members")
 
     // Some special cases when nullifying the type
-    if isEnumValueDef || sym.name == nme.TYPE_ then
-      // Don't nullify the `TYPE` field in every class and Java enum instances
+    if isEnumValueDef || sym.name == nme.TYPE_ // Don't nullify the `TYPE` field in every class and Java enum instances
+    || sym.is(Flags.ModuleVal) // Don't nullify Modules
+    then
       tp
     else if sym.name == nme.toString_ || sym.isConstructor || hasNotNullAnnot(sym) then
       // Don't nullify the return type of the `toString` method.

tests/explicit-nulls/flexible-unpickle/Flexible_2.scala

@@ -1,3 +1,6 @@
+import unsafeNulls.Foo.*
+import unsafeNulls.Unsafe_1
+
 @main
 def Flexible_2() =
   val s2: String | Null = "foo"

tests/explicit-nulls/flexible-unpickle/Unsafe_1.scala

@@ -1,6 +1,12 @@
+package unsafeNulls
+
 class Unsafe_1 {
   def foo(s: String): String = {
     if (s == null) then "nullString"
     else s
   }
 }
+
+object Foo {
+  def bar = "bar!"
+}