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/Sessions/SessionExtensions.cs

@@ -0,0 +1,60 @@
+using System;
+
+namespace EmbedIO.Sessions
+{
+    /// <summary>
+    /// Provides extension methods for types implementing <see cref="ISession"/>.
+    /// </summary>
+    public static class SessionExtensions
+    {
+        /// <summary>Gets the value associated with the specified key.</summary>
+        /// <typeparam name="T">The desired type of the value.</typeparam>
+        /// <param name="this">The <see cref="ISession"/> on which this method is called.</param>
+        /// <param name="key">The key whose value to get from the session.</param>
+        /// <param name="value">
+        /// <para>When this method returns, the value associated with the specified key,
+        /// if the key is found and the associated value is of type <typeparamref name="T"/>;
+        /// otherwise, the default value for <typeparamref name="T"/>.</para>
+        /// <para>This parameter is passed uninitialized.</para>
+        /// </param>
+        /// <returns><see langword="true"/> if the key is found and the associated value is of type <typeparamref name="T"/>;
+        /// otherwise, <see langword="false"/>.</returns>
+        /// <exception cref="NullReferenceException"><paramref name="this"/> is <see langword="null"/>.</exception>
+        /// <exception cref="ArgumentNullException"><paramref name="key"/> is <see langword="null"/>.</exception>
+        public static bool TryGetValue<T>(this ISession @this, string key, out T value)
+        {
+            if (@this.TryGetValue(key, out var foundValue) && foundValue is T typedValue)
+            {
+                value = typedValue;
+                return true;
+            }
+
+#pragma warning disable CS8653 // "default" can be null - We are returning false, so value is undefined
+            value = default;
+#pragma warning restore CS8653
+            return false;
+        }
+
+        /// <summary>Gets the value associated with the specified key.</summary>
+        /// <typeparam name="T">The desired type of the value.</typeparam>
+        /// <param name="this">The <see cref="ISession"/> on which this method is called.</param>
+        /// <param name="key">The key whose value to get from the session.</param>
+        /// <returns>The value associated with the specified key,
+        /// if the key is found and the associated value is of type <typeparamref name="T"/>;
+        /// otherwise, the default value for <typeparamref name="T"/>.</returns>
+        public static T GetValue<T>(this ISession @this, string key)
+            => @this.TryGetValue(key, out var value) && value is T typedValue ? typedValue : default;
+
+        /// <summary>Gets the value associated with the specified key.</summary>
+        /// <typeparam name="T">The desired type of the value.</typeparam>
+        /// <param name="this">The <see cref="ISession"/> on which this method is called.</param>
+        /// <param name="key">The key whose value to get from the session.</param>
+        /// <param name="defaultValue">The default value to return if the key is not found
+        /// or its associated value is not of type <typeparamref name="T"/>.</param>
+        /// <returns>The value associated with the specified key,
+        /// if the key is found and the associated value is of type <typeparamref name="T"/>;
+        /// otherwise, <paramref name="defaultValue"/>.</returns>
+        public static T GetOrDefault<T>(this ISession @this, string key, T defaultValue)
+            => @this.TryGetValue(key, out var value) && value is T typedValue ? typedValue : defaultValue;
+    }
+}