Mapster throws ArgumentNullException when mapping null collection property with LINQ method (Select), unlike AutoMapper

When migrating from AutoMapper v14 to Mapster, I encountered a difference in behavior regarding null propagation for collection properties during mapping.

In AutoMapper, if a source collection property is null, calling LINQ methods like .Select() inside a mapping expression does not throw an exception — it returns null for the destination property. However, in Mapster, the same expression throws System.ArgumentNullException: 'Value cannot be null. (Parameter 'source')'.

It seems that Mapster does not apply null propagation automatically in such cases, even though the destination property is nullable.

Reproduction Steps

apster;
using MapsterMapper;

var config = new TypeAdapterConfig();
config.ForType<Source, Destination>()
  .Map(s => s.ProductNames, d => d.Products.Select(p => p.Name).ToArray());

var mapper = new Mapper(config);

var source1 = new Source();
var destination1 = mapper.Map<Source, Destination>(source1); //throws System.ArgumentNullException: 'Value cannot be null. (Parameter 'source')

class Source
{
    public Product[]? Products { get; set; }
}

class Product
{
    public required string Name { get; set; }
}

class Destination
{
    public string[]? ProductNames { get; set; }
}

Expected Behavior

The mapping should return null for Destination.ProductNames when Source.Products is null, similar to AutoMapper's behavior. Null propagation should be applied by default, or at least be configurable.

Actual Behavior

System.ArgumentNullException: 'Value cannot be null. (Parameter 'source')' is thrown at runtime.

Environment

Mapster version: 10.0.11

Start by running the provided TypeAdapterConfig and Mapper.Map reproduction with a null Source.Products collection, then trace how the LINQ Select expression is handled during mapping. Compare the result with the stated AutoMapper behavior; done means Destination.ProductNames remains null without an ArgumentNullException, with the behavior covered by a regression test.