fix broken state on empty value lists

lib/src/common.dart

@@ -48,7 +48,8 @@ abstract class ResultState<T> extends CommonState {
       };
 
   Map<String, dynamic> get toShortMap => {
-        'value': value is Iterable ? (value as Iterable).last : value,
+        'value':
+            value is Iterable && (value as Iterable).isNotEmpty ? (value as Iterable).last : value,
         ...super.toMap,
       };