Got at least one data fetching method working; turns out, we can't use a patched LogicStack to get the data

Vendor/EmbedIO-3.5.2/Files/FileRequestHandlerCallback.cs

@@ -0,0 +1,13 @@
+using System.Threading.Tasks;
+
+namespace EmbedIO.Files
+{
+    /// <summary>
+    /// A callback used to handle a request in <see cref="FileModule"/>.
+    /// </summary>
+    /// <param name="context">An <see cref="IHttpContext"/> interface representing the context of the request.</param>
+    /// <param name="info">If the requested path has been successfully mapped to a resource (file or directory), the result of the mapping;
+    /// otherwise, <see langword="null"/>.</param>
+    /// <returns>A <see cref="Task"/> representing the ongoing operation.</returns>
+    public delegate Task FileRequestHandlerCallback(IHttpContext context, MappedResourceInfo? info);
+}