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/ModuleGroup.cs

@@ -0,0 +1,111 @@
+using System;
+using System.Collections.Concurrent;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+using EmbedIO.Internal;
+using EmbedIO.Utilities;
+
+namespace EmbedIO
+{
+    /// <summary>
+    /// <para>Groups modules under a common base URL path.</para>
+    /// <para>The <see cref="IWebModule.BaseRoute">BaseRoute</see> property
+    /// of modules contained in a <c>ModuleGroup</c> is relative to the
+    /// <c>ModuleGroup</c>'s <see cref="IWebModule.BaseRoute">BaseRoute</see> property.
+    /// For example, given the following code:</para>
+    /// <para><code>new ModuleGroup("/download")
+    ///     .WithStaticFilesAt("/docs", "/var/my/documents");</code></para>
+    /// <para>files contained in the <c>/var/my/documents</c> folder will be
+    /// available to clients under the <c>/download/docs/</c> URL.</para>
+    /// </summary>
+    /// <seealso cref="WebModuleBase" />
+    /// <seealso cref="IDisposable" />
+    /// <seealso cref="IWebModuleContainer" />
+    public class ModuleGroup : WebModuleBase, IDisposable, IWebModuleContainer, IMimeTypeCustomizer
+    {
+        private readonly WebModuleCollection _modules;
+        private readonly MimeTypeCustomizer _mimeTypeCustomizer = new MimeTypeCustomizer();
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="ModuleGroup" /> class.
+        /// </summary>
+        /// <param name="baseRoute">The base route served by this module.</param>
+        /// <param name="isFinalHandler">The value to set the <see cref="IWebModule.IsFinalHandler" /> property to.
+        /// See the help for the property for more information.</param>
+        /// <seealso cref="IWebModule.BaseRoute" />
+        /// <seealso cref="IWebModule.IsFinalHandler" />
+        public ModuleGroup(string baseRoute, bool isFinalHandler)
+            : base(baseRoute)
+        {
+            IsFinalHandler = isFinalHandler;
+            _modules = new WebModuleCollection(nameof(ModuleGroup));
+        }
+
+        /// <summary>
+        /// Finalizes an instance of the <see cref="ModuleGroup"/> class.
+        /// </summary>
+        ~ModuleGroup()
+        {
+            Dispose(false);
+        }
+
+        /// <inheritdoc />
+        public sealed override bool IsFinalHandler { get; }
+
+        /// <inheritdoc />
+        public IComponentCollection<IWebModule> Modules => _modules;
+
+        /// <inheritdoc />
+        public void Dispose()
+        {
+            Dispose(true);
+            GC.SuppressFinalize(this);
+        }
+
+        string IMimeTypeProvider.GetMimeType(string extension)
+            => _mimeTypeCustomizer.GetMimeType(extension);
+
+        bool IMimeTypeProvider.TryDetermineCompression(string mimeType, out bool preferCompression)
+            => _mimeTypeCustomizer.TryDetermineCompression(mimeType, out preferCompression);
+
+        /// <inheritdoc />
+        public void AddCustomMimeType(string extension, string mimeType)
+            => _mimeTypeCustomizer.AddCustomMimeType(extension, mimeType);
+
+        /// <inheritdoc />
+        public void PreferCompression(string mimeType, bool preferCompression)
+            => _mimeTypeCustomizer.PreferCompression(mimeType, preferCompression);
+
+        /// <inheritdoc />
+        protected override Task OnRequestAsync(IHttpContext context)
+            => _modules.DispatchRequestAsync(context);
+
+        /// <summary>
+        /// Releases unmanaged and - optionally - managed resources.
+        /// </summary>
+        /// <param name="disposing"><see langword="true"/> to release both managed and unmanaged resources;
+        /// <see langword="false"/> to release only unmanaged resources.</param>
+        protected virtual void Dispose(bool disposing)
+        {
+            if (!disposing)
+                return;
+
+            _modules.Dispose();
+        }
+
+        /// <inheritdoc />
+        protected override void OnBeforeLockConfiguration()
+        {
+            base.OnBeforeLockConfiguration();
+
+            _mimeTypeCustomizer.Lock();
+        }
+
+        /// <inheritdoc />
+        protected override void OnStart(CancellationToken cancellationToken)
+        {
+            _modules.StartAll(cancellationToken);
+        }
+    }
+}