1.3.2: Marked SerializeReferenceTo to be 2019_3_OR_NEWER

Editor/Drawers/SerializableReferenceToAttributeDrawer.cs

@@ -1,4 +1,5 @@
-using System;
+#if UNITY_2019_3_OR_NEWER
+using System;
 using System.Reflection;
 using System.Runtime.Serialization;
 using Module.Inspector.Editor.Utilities;
@@ -152,3 +153,4 @@ namespace Module.Inspector.Editor
         }
     }
 }
+#endif

Runtime/Drawers/SerializableReferenceToAttribute.cs

@@ -1,4 +1,5 @@
-using System;
+#if UNITY_2019_3_OR_NEWER
+using System;
 
 namespace Module.Inspector
 {
@@ -20,3 +21,4 @@ namespace Module.Inspector
         }
     }
 }
+#endif

package.json

@@ -1,6 +1,6 @@
 {
   "name": "com.module.inspector",
-  "version": "1.3.1",
+  "version": "1.3.2",
   "displayName": "Module.Inspector",
   "description": "Custom inspector with various useful property drawers",
   "unity": "2019.2",