--- 
+++ 
@@ -13,7 +13,7 @@
                     JavaType actual = _handleUnknownTypeId(ctxt, typeId);
                     if (actual == null) { // what should this be taken to mean?
                         // 17-Jan-2019, tatu: As per [databind#2221], better NOT return `null` but...
-                        return null;
+                        return NullifyingDeserializer.instance;
                     }
                     // ... would this actually work?
                     deser = ctxt.findContextualValueDeserializer(actual, _property);