Invalid mapping for nullable arrays

[TonEnfer]

Describe the bug Mapperly generates incorrect code for nullable arrays in some cases. See example code

Declaration code

public record Dto(int[]? Array);

[Mapper]
public partial class Mapper
{
    public partial Dto Map(int[]? array);
    public partial int[]? Map(int[]? model);
}

Actual relevant generated code

// <auto-generated />
#nullable enable
namespace ConsoleApp1
{
    public partial class Mapper
    {
        [global::System.CodeDom.Compiler.GeneratedCode("Riok.Mapperly", "4.1.1.0")]
        public partial global::ConsoleApp1.Dto Map(int[]? model)
        {
            return model == null ? throw new System.ArgumentNullException(nameof(model)) : new global::ConsoleApp1.Dto(model);
        }

        [global::System.CodeDom.Compiler.GeneratedCode("Riok.Mapperly", "4.1.1.0")]
        public partial int[]? Map(int[]? model)
        {
            return model == null ? default : model;
        }
    }
}

Expected relevant generated code

// <auto-generated />
#nullable enable
namespace ConsoleApp1
{
    public partial class Mapper
    {
        [global::System.CodeDom.Compiler.GeneratedCode("Riok.Mapperly", "4.1.1.0")]
        public partial global::ConsoleApp1.Dto Map(int[]? model)
        {
            return new global::ConsoleApp1.Dto(model);
        }

        [global::System.CodeDom.Compiler.GeneratedCode("Riok.Mapperly", "4.1.1.0")]
        public partial int[]? Map(int[]? model)
        {
            return model;
        }
    }
}

Environment (please complete the following information):

• Mapperly Version: 4.1.1.0
• Nullable reference types: enabled
• .NET Version: 9.0.100
• Target Framework: .net9.0
• Compiler Version: 4.12.0-3.24558.5 (21192bfc)
• C# Language Version: 13.0
• IDE: Visual Studio 17.12.1
• OS: Win 11

[latonz]

Thank you for reporting this issue! It seems there are some bugs related to our null handling. I've created #1614 to address this and explore ways to improve our approach to null handling in general.