Merge branch 'maurocerutti-FixDbStringList'

Dapper NET40/SqlMapper.cs

@@ -2605,7 +2605,6 @@ public static void PackListParameters(IDbCommand command, string namePrefix, obj
                     count++;
                     var listParam = command.CreateParameter();
                     listParam.ParameterName = namePrefix + count;
-                    listParam.Value = item ?? DBNull.Value;
                     if (isString)
                     {
                         listParam.Size = DbString.DefaultLength;
@@ -2621,6 +2620,7 @@ public static void PackListParameters(IDbCommand command, string namePrefix, obj
                     }
                     else
                     {
+                        listParam.Value = item ?? DBNull.Value;
                         command.Parameters.Add(listParam);
                     }
                 }