Incorrect nullability of KObject and KValue indexer

[TheBoxyBear]

From the NuGet package:

When calling the key indexer of a KVObject or KVValue, VS Intellisense indicates that the indexer will return a non-null KVValue, even if nullability is nullable reference types are enabled at the file or project level.

This goes against the actual behavior of the indexer, which returns a null KVValue if the key is not present in the collection. It therefore leads to misunderstanding of the library behavior, both by the user and by code analysis which fails to detect null-unsafe usages of KVValue.

[TheBoxyBear]

After cloning the repo, it seems the deviation in nullability starts at KVCollectionValue.Get

public KVObject Get(string name)
{
    ArgumentNullException.ThrowIfNull(name);
    return children.FirstOrDefault(c => c.Name == name);
}

FirstOrDefault returns a nullable KVObject, but code analysis fails to recognize the unsafe operation or returning it when the declared return type is non-nullable.

To avoid making the entire project null-safe considering warnings are treated as errors, nullability could be implemented on a per-file basis with the #nullable enable preprocessor directive.