Additional mapping method parameter not mapped when source/target is nullable

[kockicica]

Please do the checklist before filing an issue:

• I have read the documentation, including the FAQ
• I can reproduce the bug using the latest prerelease version
• I have searched existing discussion and issue to avoid duplicates

Describe the bug
When the mapping source/target is nullable and the mapping method has an additional parameter, that parameter is either ignored entirely (when [MapperIgnoreSource] is present) or silently dropped from the generated code (when it's absent). The id parameter should be mapped to target.Id but is not.

5.0.0-next.3 works fine - expected generated code is actually from next.3 version.

Repro
Same repository demonstrates the issue: https://github.com/kockicica/mapperly-test

Declaration code

[Mapper]
public partial class Mapper
{
    [MapperIgnoreSource(nameof(@Model.Scenario.Id))]
    public partial Data.Scenario? ModelToEntity(Model.Scenario? source, Guid? id=null);
    
    
}

Actual relevant generated code

    [global::System.CodeDom.Compiler.GeneratedCode("Riok.Mapperly", "5.0.0.0")]
    [return: global::System.Diagnostics.CodeAnalysis.NotNullIfNotNull(nameof(source))]
    public partial global::Data.Scenario? ModelToEntity(global::Model.Scenario? source, global::System.Guid? id)
    {
        if (source == null)
            return default;
        var target = new global::Data.Scenario();
        target.Name = source.Name;
        target.Description = source.Description;
        target.AudioFileName = source.AudioFileName;
        target.AudioFilePath = source.AudioFilePath;
        if (source.Actions != null)
        {
            target.Actions = MapToListOfScenarioAction(source.Actions);
        }
        else
        {
            target.Actions = null;
        }
        return target;
    }

Expected relevant generated code

    [global::System.CodeDom.Compiler.GeneratedCode("Riok.Mapperly", "5.0.0.0")]
    [return: global::System.Diagnostics.CodeAnalysis.NotNullIfNotNull(nameof(source))]
    public partial global::Data.Scenario? ModelToEntity(global::Model.Scenario? source, global::System.Guid? id)
    {
        if (source == null)
            return default;
        var target = new global::Data.Scenario();
        if (id != null)
        {
            target.Id = id.Value;
        }
        target.Name = source.Name;
        target.Description = source.Description;
        target.AudioFileName = source.AudioFileName;
        target.AudioFilePath = source.AudioFilePath;
        if (source.Actions != null)
        {
            target.Actions = MapToListOfScenarioAction(source.Actions);
        }
        else
        {
            target.Actions = null;
        }
        return target;
    }

Environment (please complete the following information):

• Mapperly Version: 5.0.0-next.6
• Target Framework: net10.0
• Compiler Version: 5.3.0-2.26153.122 (4d3023de605a78ba3e59e50c657eed70f125c68a)
• C# Language Version: 14.0
• OS: Windows 11