Fixed manifest filter after cherry picking from v13/main

src/Skybrud.Essentials.Umbraco/EssentialsManifestFilter.cs

@@ -1,4 +1,5 @@
 using System.Collections.Generic;
+using System.Reflection;
 using Umbraco.Cms.Core.Manifest;
 
 namespace Skybrud.Essentials.Umbraco;
@@ -8,9 +9,10 @@ public class EssentialsManifestFilter : IManifestFilter {
 
     /// <inheritdoc />
     public void Filter(List<PackageManifest> manifests) {
-        manifests.Add(new PackageManifest {
+
+        // Initialize a new manifest filter for this package
+        PackageManifest manifest = new() {
             AllowPackageTelemetry = false,
-            PackageId = EssentialsPackage.Alias,
             PackageName = EssentialsPackage.Name,
             Version = EssentialsPackage.InformationalVersion,
             Scripts = [
@@ -20,7 +22,21 @@ public void Filter(List<PackageManifest> manifests) {
             Stylesheets = [
                 $"/App_Plugins/{EssentialsPackage.AppPlugins}/Styles/Styles.css"
             ]
-        });
+        };
+
+        // The "PackageId" property isn't available prior to Umbraco 12, and since the package is build against
+        // Umbraco 10, we need to use reflection for setting the property value for Umbraco 12+. Ideally this
+        // shouldn't fail, but we might at least add a try/catch to be sure
+        try {
+            PropertyInfo? property = manifest.GetType().GetProperty("PackageId");
+            property?.SetValue(manifest, EssentialsPackage.Alias);
+        } catch {
+            // We don't really care about the exception
+        }
+
+        // Append the manifest
+        manifests.Add(manifest);
+
     }
 
 }