[IR] Pass null instead of IrUninitializedType to IrFactory

#KT-66053 In progress

compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrDeclarationDeserializer.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2020 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Copyright 2010-2024 JetBrains s.r.o. and Kotlin Programming Language contributors.
  * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
  */
 
@@ -611,7 +611,7 @@ class IrDeclarationDeserializer(
                     visibility = flags.visibility,
                     isInline = flags.isInline,
                     isExpect = flags.isExpect,
-                    returnType = IrUninitializedType,
+                    returnType = null,
                     modality = flags.modality,
                     symbol = it,
                     isTailrec = flags.isTailrec,
@@ -685,7 +685,7 @@ class IrDeclarationDeserializer(
                     visibility = flags.visibility,
                     isInline = flags.isInline,
                     isExpect = flags.isExpect,
-                    returnType = IrUninitializedType,
+                    returnType = null,
                     symbol = it,
                     isPrimary = flags.isPrimary,
                     isExternal = flags.isExternal || isEffectivelyExternal,