Fix explicit null matching issue

Author: HarrisL2

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

@@ -970,7 +970,6 @@ class TypeComparer(@constructorOnly initctx: Context) extends ConstraintHandling
             def isNullable(tp: Type): Boolean = tp.dealias match
               case tp: TypeRef =>
                 val tpSym = tp.symbol
-                !tpSym.isPrimitiveValueClass ||
                 tpSym.isNullableClass
               case tp: TermRef =>
                 // https://scala-lang.org/files/archive/spec/2.13/03-types.html#singleton-types

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

@@ -1193,7 +1193,8 @@ object Types extends TypeUtils {
      */
     def matches(that: Type)(using Context): Boolean = {
       record("matches")
-      TypeComparer.matchesType(this, that, relaxed = !ctx.phase.erasedTypes)
+      withoutMode(Mode.SafeNulls)(
+        TypeComparer.matchesType(this, that, relaxed = !ctx.phase.erasedTypes))
     }
 
     /** This is the same as `matches` except that it also matches => T with T and