various fixes

src/Avalonia.Base/Visual.cs

@@ -667,8 +667,14 @@ namespace Avalonia
 
             if (_visualParent is IRenderRoot || _visualParent?.IsAttachedToVisualTree == true)
             {
-                var root = this.FindAncestorOfType<IRenderRoot>() ??
-                    throw new AvaloniaInternalException("Visual is atached to visual tree but root could not be found.");
+                var root = this.FindAncestorOfType<IRenderRoot>();
+                if (root is null)
+                {
+                    Logger.TryGet(LogEventLevel.Error, "Visual")?.Log("Visual",
+                        "Visual is atached to visual tree but root could not be found.");
+                    return;
+                }
+
                 var e = new VisualTreeAttachmentEventArgs(_visualParent, root);
                 OnAttachedToVisualTreeCore(e);
             }

src/Avalonia.OpenGL/Controls/OpenGlControlBase.cs

@@ -148,6 +148,13 @@ namespace Avalonia.OpenGL.Controls
                 return false;
             }
 
+            if (_context == null)
+            {
+                Logger.TryGet(LogEventLevel.Error, "OpenGL")?.Log("OpenGlControlBase",
+                    "Unable to initialize OpenGL: unable to create additional OpenGL context.");
+                return false;
+            }
+
             GlVersion = _context.Version;
             try
             {