Fix case 1294180 : Error feedback throwing an error while changing capacity (#174)

Issue introduced with https://github.cds.internal.unity3d.com/unity/vfx-graphics/pull/136
And more precisely https://github.cds.internal.unity3d.com/unity/vfx-graphics/pull/136/commits/27c041da92ec89407ae775fe4c4f24681f156cb8

Author: PaulDemeulenaere

com.unity.visualeffectgraph/CHANGELOG.md

@@ -6,16 +6,13 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ## [11.0.0] - 2020-10-21
 ### Added
+- Added new setting to output nodes to exclude from TAA
 - Changed the "Edit" button so it becomes "New" when no asset is set on a Visual Effect component, in order to save a new visual effect graph asset.
 
 ### Fixed
 - Forbid incorrect link between incompatible context [Case 1269756](https://issuetracker.unity3d.com/product/unity/issues/guid/1269756/)
 - Serialization issue with VFXSpawnerCallbacks
-
-### Added
-- Added new setting to output nodes to exclude from TAA
-
-### Fixed
+- Unexpected exception while trying to display capacity warning [Case 1294180](https://issuetracker.unity3d.com/product/unity/issues/guid/1294180/)
 
 ## [10.2.0] - 2020-10-19
 ### Added

com.unity.visualeffectgraph/Editor/GraphView/Views/VFXView.cs

@@ -631,16 +631,20 @@ private void RegisterError(VFXModel model, VFXErrorOrigin errorOrigin, string er
                         return;
                     targetParent = targetContext.parent;
                 }
+                else
+                {
+                    targetParent = target.parent;
+                }
                 target = (target as VFXNodeUI).titleContainer;
                 alignement = SpriteAlignment.LeftCenter;
             }
-            if (target != null)
+
+            if (target != null && targetParent != null)
             {
                 var badge = type == VFXErrorType.Error ? IconBadge.CreateError(description) : IconBadge.CreateComment(description);
                 targetParent.Add(badge);
                 badge.AttachTo(target, alignement);
 
-
                 if (errorOrigin == VFXErrorOrigin.Compilation)
                 {
                     m_CompileBadges.Add(badge);