Kentico 13 - write to ViewContext from inlinewidgetpage

Question

I am using DevTrev's PartialWidgetPage to recreate the MasterPage functionality of previous Kentico versions.

The Nav and Footer get rendered into the _Layout.cshtml as expected but I have another component/widget in the master page that uses a HtmlHelper extension to write to _Layout.cshtml in a similar way to to @RenderSection() does.

The widget works fine when it is placed in a normal page but when it's in a page rendered by the PartialWidgetPage, it doesn't get written to _Layout.cshtml.

The helper extension is as follows:

public static class HtmlHelperExtensions
{
    private static IHttpContextAccessor httpContextAccessor;
    public static HtmlString AddResource(this IHtmlHelper htmlHelper, PageResourceType resourceType, string identifier, Func<object, HelperResult> template)
    {
        httpContextAccessor = Service.Resolve<IHttpContextAccessor>();
        if (httpContextAccessor.HttpContext.Items[resourceType] != null)
        {
            ((List<(Func<object, HelperResult>, string)>)httpContextAccessor.HttpContext.Items[resourceType]).Add((template, identifier));
        }
        else
        {
            httpContextAccessor.HttpContext.Items[resourceType] = new List<(Func<object, HelperResult>, string)>() { (template, identifier) };
        }

        return new HtmlString(string.Empty);
    }

    public static HtmlString RenderResources(this IHtmlHelper htmlHelper, PageResourceType resourceType)
    {
        httpContextAccessor = Service.Resolve<IHttpContextAccessor>();
        if (httpContextAccessor.HttpContext.Items[resourceType] != null)
        {
            List<(Func<object, HelperResult>, string)> resources = (List<(Func<object, HelperResult>, string)>)httpContextAccessor.HttpContext.Items[resourceType];

            foreach (var resource in resources.DistinctBy(r => r.Item2))
            {
                if (resource.Item1 != null)
                {
                    htmlHelper.ViewContext.Writer.Write(resource.Item1(null));
                }
            }
        }

        return new HtmlString(string.Empty);
    }
}

And is called in _Layout.cshtml like so:

@Html.RenderResources(PageResourceType.HeadScript)