Make AuthenticateWithLogin throw instead of return a bool success status

osu.Game/Graphics/ErrorTextFlowContainer.cs

@@ -0,0 +1,35 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System.Collections.Generic;
+using osu.Framework.Graphics;
+using osu.Game.Graphics.Containers;
+using osuTK.Graphics;
+
+namespace osu.Game.Graphics
+{
+    public class ErrorTextFlowContainer : OsuTextFlowContainer
+    {
+        private readonly List<Drawable> errorDrawables = new List<Drawable>();
+
+        public ErrorTextFlowContainer()
+            : base(cp => cp.Font = cp.Font.With(size: 12))
+        {
+        }
+
+        public void ClearErrors()
+        {
+            errorDrawables.ForEach(d => d.Expire());
+        }
+
+        public void AddErrors(string[] errors)
+        {
+            ClearErrors();
+
+            if (errors == null) return;
+
+            foreach (var error in errors)
+                errorDrawables.AddRange(AddParagraph(error, cp => cp.Colour = Color4.Red));
+        }
+    }
+}