Enable & fix up any nullable type issues

Author: Warren Buckley

Our.Umbraco.TagHelpers/ActiveClassTagHelper.cs

@@ -35,7 +35,7 @@ public ActiveClassTagHelper(IUmbracoContextAccessor umbracoContextAccessor)
         /// on an <a> tag when the page is active/selected
         /// </summary>
         [HtmlAttributeName(tagHelperAttributeName)]
-        public string ActiveClassName { get; set; }
+        public string? ActiveClassName { get; set; }
 
 
         /// <summary>
@@ -62,7 +62,7 @@ public override void Process(TagHelperContext context, TagHelperOutput output)
 
             // Try & parse href as URI, as it could be relative or absolute
             // or contain a quersystring we only want the path part
-            if (Uri.TryCreate(href, UriKind.Absolute, out Uri link) || Uri.TryCreate(ctx.PublishedRequest.Uri, href, out link))
+            if (Uri.TryCreate(href, UriKind.Absolute, out Uri? link) || Uri.TryCreate(ctx.PublishedRequest.Uri, href, out link))
             {
                 // Get the node based of the value in the HREF
                 var nodeOfLink = ctx.Content.GetByRoute(link.AbsolutePath);

Our.Umbraco.TagHelpers/Our.Umbraco.TagHelpers.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
 	<PropertyGroup>
-		<TargetFrameworks>net5.0;net6.0</TargetFrameworks>
+		<TargetFrameworks>net5.0;net6.0;</TargetFrameworks>
 	</PropertyGroup>
 
 	<PropertyGroup>
@@ -29,6 +29,7 @@
 		<PackageIcon>TagHelperLogo.png</PackageIcon>
 		<PackageTags>Umbraco;TagHelper;TagHelpers;UmbracoCMS</PackageTags>
 		<PackageReadmeFile>README.md</PackageReadmeFile>
+		<Nullable>enable</Nullable>
 	</PropertyGroup>
 
 	<ItemGroup>