Dapper.Contrib "Insert" throws "Cannot convert null to 'int' because it is a non-nullable value type" when trying to call insert extension method while not using identity column at database

this is the issue. create a table in the database without identity column. create its poco class and try to call insert method.
I would like to set id column from my application. that is why i am not using identity column.

i fould the reason when i debug the code. After I call Insert extension method, it tries to return @@Identity value as integer. but because of id is not identity, it returns null. so i get "Cannot convert null to 'int' because it is a non-nullable value type" exception message.

CREATE TABLE User(
    [Id] [int] Primary key NOT NULL ,
    [Name] nvarchar(50) NOT NULL
)

public class User
{
 public Int32 Id {get;set;}
 public String Name {get;set;}
}

using Dapper.Contrib.Extensions;

var connStr = "bla bla";
var connection = new SqlConnection(connStr);
connection.Open();
connection.Insert(new User { Id = 1, Name="Tugbay" });
connection.Close();

Start at the Dapper.Contrib Insert extension method and reproduce the issue with the SQL table and C# User class shown in the report. Trace how the insert handles @@Identity when the Id is supplied by the application; done means inserting a row without an identity column no longer fails while identity-column inserts remain supported.