Use CSharp Script in Blazor WASM - Assembly load error

[marc-mueller]

Dear Blazor Experts

We'd like to port an application to client side Blazor which contains business logic which needs to be evaluated during runtime. Therefore we used the Roslyn CSharpScript evaluation to parse delegate expression. Doing that with WASM does not work. It cannot load the assembly correctly since the path is empty. Is this not working at all or do I miss something here? Thanks for your help!

Simplified Repro Code:

    public Func<string> SayHello { get; set; }

    protected override async Task OnInitializedAsync()
    {
        var statement = "() => \"Hello from script\"";
        var scriptOptions = ScriptOptions.Default;
        var assemblies = AppDomain.CurrentDomain.GetAssemblies();

        using var client = new HttpClient
        {
            BaseAddress = new Uri("https://localhost:44378")
        };

        var response = await client.GetFromJsonAsync<BlazorBoot>("_framework/blazor.boot.json").ConfigureAwait(false);
        var assemblies2 = await Task.WhenAll(response.resources.assembly.Keys.Select(x => client.GetAsync("_framework/_bin/" + x))).ConfigureAwait(false);

        var references2 = new List<MetadataReference>(assemblies.Length);
        foreach (var asm in assemblies2)
        {
            using (var task = await asm.Content.ReadAsStreamAsync().ConfigureAwait(false))
            {
                scriptOptions = scriptOptions.AddReferences(MetadataReference.CreateFromStream(task));
            }
        }

        scriptOptions = scriptOptions.AddImports("System");
        scriptOptions = scriptOptions.AddImports("System.Collections.Generic");
        scriptOptions = scriptOptions.AddImports("System.Threading");
        scriptOptions = scriptOptions.AddImports("System.Threading.Tasks");

        try
        {
            var result = await CSharpScript.EvaluateAsync<Func<string>>(statement, scriptOptions).ConfigureAwait(false);
            SayHello = result;
        }
        catch (Exception ex)
        {
            Debug.WriteLine(ex.ToString());
            throw;
        }
    }

    private class BlazorBoot
    {
        public bool cacheBootResources { get; set; }
        public object[] config { get; set; }
        public bool debugBuild { get; set; }
        public string entryAssembly { get; set; }
        public bool linkerEnabled { get; set; }
        public Resources resources { get; set; }
    }

    private class Resources
    {
        public Dictionary<string, string> assembly { get; set; }
        public Dictionary<string, string> pdb { get; set; }
        public Dictionary<string, string> runtime { get; set; }
    }

Error:

Unhandled exception rendering component: The type initializer for 'Microsoft.CodeAnalysis.Scripting.ScriptOptions' threw an exception.
System.TypeInitializationException: The type initializer for 'Microsoft.CodeAnalysis.Scripting.ScriptOptions' threw an exception. ---> System.TypeInitializationException: The type initializer for 'Microsoft.CodeAnalysis.Scripting.ScriptMetadataResolver' threw an exception. ---> System.TypeInitializationException: The type initializer for 'Microsoft.CodeAnalysis.GlobalAssemblyCache' threw an exception. ---> System.TypeInitializationException: The type initializer for 'Microsoft.CodeAnalysis.MonoGlobalAssemblyCache' threw an exception. ---> System.ArgumentException: Path cannot be the empty string or all whitespace.
Parameter name: path
  at System.IO.Directory.GetParent (System.String path) <0x39db288 + 0x00036> in <filename unknown>:0