- Add XamlLoadException

- Use it for the new load exception info.

src/Markup/Avalonia.Markup.Xaml/Avalonia.Markup.Xaml.csproj

@@ -91,6 +91,7 @@
         <Compile Include="Templates\TemplateContent.cs" />
         <Compile Include="Templates\TemplateLoader.cs" />
         <Compile Include="Templates\TreeDataTemplate.cs" />
+        <Compile Include="XamlLoadException.cs" />
         <Compile Include="PortableXaml\portable.xaml.github\src\Portable.Xaml\**\*.cs" Exclude="PortableXaml\portable.xaml.github\src\Portable.Xaml\Assembly\**\*.cs" />
         <Compile Remove="**\UriTypeConverter.cs" />
     </ItemGroup>

src/Markup/Avalonia.Markup.Xaml/AvaloniaXamlLoaderPortableXaml.cs

@@ -138,7 +138,7 @@ namespace Avalonia.Markup.Xaml
                     {
                         uriString = new Uri(baseUri, uri).AbsoluteUri;
                     }
-                    throw new Exception("Error loading xaml at " + uriString, e);
+                    throw new XamlLoadException("Error loading xaml at " + uriString, e);
                 }
             }
         }