Fixed attached files silently reaching the AI as empty documents (#904)

app/MindWork AI Studio/Tools/ContentStreamErrorMetadata.cs

@@ -0,0 +1,11 @@
+using System.Text.Json.Serialization;
+
+namespace AIStudio.Tools;
+
+// ReSharper disable UnusedAutoPropertyAccessor.Global
+// ReSharper disable ClassNeverInstantiated.Global
+public sealed class ContentStreamErrorMetadata : ContentStreamSseMetadata
+{
+    [JsonPropertyName("Error")]
+    public ContentStreamErrorDetails? Error { get; init; }
+}