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/ResponseSerializerCallback.cs

@@ -0,0 +1,12 @@
+using System.Threading.Tasks;
+
+namespace EmbedIO
+{
+    /// <summary>
+    /// A callback used to serialize data to a HTTP response.
+    /// </summary>
+    /// <param name="context">The HTTP context of the request.</param>
+    /// <param name="data">The data to serialize.</param>
+    /// <returns>A <see cref="Task"/> representing the ongoing operation.</returns>
+    public delegate Task ResponseSerializerCallback(IHttpContext context, object? data);
+}