UnityEditor.Graphs.Edge.WakeUp ()(at UnityEditor.Graphs/Edge.cs:114)でNullReferenceException

Unityエディタで以下のエラーが出ました。

NullReferenceException: Object reference not set to an instance of an object
UnityEditor.Graphs.Edge.WakeUp ()
(at /Users/builduser/buildslave/unity/build/Editor/Graphs/UnityEditor.Graphs/Edge.cs:114)
UnityEditor.Graphs.Graph.DoWakeUpEdges (System.Collections.Generic.List`1 inEdges, System.Collections.Generic.List`1 ok, System.Collections.Generic.List`1 error, Boolean inEdgesUsedToBeValid)
(at /Users/builduser/buildslave/unity/build/Editor/Graphs/UnityEditor.Graphs/Graph.cs:387)
UnityEditor.Graphs.Graph.WakeUpEdges (Boolean clearSlotEdges)
(at /Users/builduser/buildslave/unity/build/Editor/Graphs/UnityEditor.Graphs/Graph.cs:286)
UnityEditor.Graphs.Graph.WakeUp (Boolean force)
(at /Users/builduser/buildslave/unity/build/Editor/Graphs/UnityEditor.Graphs/Graph.cs:272)
UnityEditor.Graphs.Graph.WakeUp ()
(at /Users/builduser/buildslave/unity/build/Editor/Graphs/UnityEditor.Graphs/Graph.cs:250)
UnityEditor.Graphs.Graph.OnEnable ()
(at /Users/builduser/buildslave/unity/build/Editor/Graphs/UnityEditor.Graphs/Graph.cs:245)

解決方法

なぜこんなエラーが出たのかはよく分かりません。が、調べたところUnityを再起動すれば直るとのこと。

実際再起動してみると、無事直りました。