Steps to reproduce:
1. Open QA-attached project (in Notes)
2. Select "The Joint" GameObject
3. Move it around with the Rect Transform tool

Expected: No errors are thrown
Actual: NullReferenceException* is spammed in the Console window

Reproduced in: 2017.4.10f1, 2018.1.9f2, 2018.2.7f1, 2018.3.0a11

Notes: Setting the Sprite to something on the SpringJoint2D RigidBody reference fixes the issue

Link to Video and Project due to not being able to upload files to FogBugz:
Video: https://drive.google.com/file/d/1uwjAO-4mIgAYVLA-Pw0etW-d5R7s4LCM/view?usp=sharing
Project: https://drive.google.com/file/d/11N5jrpWNlMaZuxyIDzPrXDbsPGjMe57t/view?usp=sharing

Full error:
* NullReferenceException: Object reference not set to an instance of an object
UnityEditor.Joint2DEditor.SnapToSprite (UnityEngine.SpriteRenderer spriteRenderer, UnityEngine.Vector3 position, System.Single snapDistance) (at C:/buildslave/unity/build/Editor/Mono/Inspector/Joint2DEditor.cs:151)
UnityEditor.AnchoredJoint2DEditor.SnapToSprites (UnityEngine.Vector3 position) (at C:/buildslave/unity/build/Editor/Mono/Inspector/AnchoredJoint2DEditor.cs:63)
UnityEditor.AnchoredJoint2DEditor.OnSceneGUI () (at C:/buildslave/unity/build/Editor/Mono/Inspector/AnchoredJoint2DEditor.cs:47)
UnityEditor.SpringJoint2DEditor.OnSceneGUI () (at C:/buildslave/unity/build/Editor/Mono/Inspector/SpringJoint2DEditor.cs:28)
System.Reflection.MonoMethod.Invoke (System.Object obj, System.Reflection.BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) (at <ac823e2bb42b41bda67924a45a0173c3>:0)
Rethrow as TargetInvocationException: Exception has been thrown by the target of an invocation.
System.Reflection.MonoMethod.Invoke (System.Object obj, System.Reflection.BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) (at <ac823e2bb42b41bda67924a45a0173c3>:0)
System.Reflection.MethodBase.Invoke (System.Object obj, System.Object[] parameters) (at <ac823e2bb42b41bda67924a45a0173c3>:0)
UnityEditor.SceneView.CallOnSceneGUI () (at C:/buildslave/unity/build/Editor/Mono/SceneView/SceneView.cs:2789)
UnityEditor.SceneView.HandleSelectionAndOnSceneGUI () (at C:/buildslave/unity/build/Editor/Mono/SceneView/SceneView.cs:2076)
UnityEditor.SceneView.OnGUI () (at C:/buildslave/unity/build/Editor/Mono/SceneView/SceneView.cs:1937)
System.Reflection.MonoMethod.Invoke (System.Object obj, System.Reflection.BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) (at <ac823e2bb42b41bda67924a45a0173c3>:0)
Rethrow as TargetInvocationException: Exception has been thrown by the target of an invocation.
System.Reflection.MonoMethod.Invoke (System.Object obj, System.Reflection.BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) (at <ac823e2bb42b41bda67924a45a0173c3>:0)
System.Reflection.MethodBase.Invoke (System.Object obj, System.Object[] parameters) (at <ac823e2bb42b41bda67924a45a0173c3>:0)
UnityEditor.HostView.Invoke (System.String methodName, System.Object obj) (at C:/buildslave/unity/build/Editor/Mono/HostView.cs:335)
UnityEditor.HostView.Invoke (System.String methodName) (at C:/buildslave/unity/build/Editor/Mono/HostView.cs:329)
UnityEditor.HostView.InvokeOnGUI (UnityEngine.Rect onGUIPosition, UnityEngine.Rect viewRect) (at C:/buildslave/unity/build/Editor/Mono/HostView.cs:303)
UnityEditor.DockArea.DrawView (UnityEngine.Rect viewRect, UnityEngine.Rect dockAreaRect, System.Boolean customBorder, System.Boolean floatingWindow, System.Boolean isBottomTab) (at C:/buildslave/unity/build/Editor/Mono/GUI/DockArea.cs:360)
UnityEditor.DockArea.OldOnGUI () (at C:/buildslave/unity/build/Editor/Mono/GUI/DockArea.cs:319)
UnityEngine.Experimental.UIElements.IMGUIContainer.DoOnGUI (UnityEngine.Event evt, UnityEngine.Matrix4x4 worldTransform, UnityEngine.Rect clippingRect, System.Boolean isComputingLayout) (at C:/buildslave/unity/build/Modules/UIElements/IMGUIContainer.cs:266)
UnityEngine.Experimental.UIElements.IMGUIContainer.HandleIMGUIEvent (UnityEngine.Event e, UnityEngine.Matrix4x4 worldTransform, UnityEngine.Rect clippingRect) (at C:/buildslave/unity/build/Modules/UIElements/IMGUIContainer.cs:438)
UnityEngine.Experimental.UIElements.IMGUIContainer.HandleIMGUIEvent (UnityEngine.Event e) (at C:/buildslave/unity/build/Modules/UIElements/IMGUIContainer.cs:421)
UnityEngine.Experimental.UIElements.IMGUIContainer.HandleEvent (UnityEngine.Experimental.UIElements.EventBase evt) (at C:/buildslave/unity/build/Modules/UIElements/IMGUIContainer.cs:401)
UnityEngine.Experimental.UIElements.EventDispatcher.ProcessEvent (UnityEngine.Experimental.UIElements.EventBase evt, UnityEngine.Experimental.UIElements.IPanel panel) (at C:/buildslave/unity/build/Modules/UIElements/EventDispatcher.cs:511)
UnityEngine.Experimental.UIElements.EventDispatcher.Dispatch (UnityEngine.Experimental.UIElements.EventBase evt, UnityEngine.Experimental.UIElements.IPanel panel, UnityEngine.Experimental.UIElements.DispatchMode dispatchMode) (at C:/buildslave/unity/build/Modules/UIElements/EventDispatcher.cs:307)
UnityEngine.Experimental.UIElements.BaseVisualElementPanel.SendEvent (UnityEngine.Experimental.UIElements.EventBase e, UnityEngine.Experimental.UIElements.DispatchMode dispatchMode) (at C:/buildslave/unity/build/Modules/UIElements/Panel.cs:176)
UnityEngine.Experimental.UIElements.UIElementsUtility.DoDispatch (UnityEngine.Experimental.UIElements.BaseVisualElementPanel panel) (at C:/buildslave/unity/build/Modules/UIElements/UIElementsUtility.cs:245)
UnityEngine.Experimental.UIElements.UIElementsUtility.ProcessEvent (System.Int32 instanceID, System.IntPtr nativeEventPtr) (at C:/buildslave/unity/build/Modules/UIElements/UIElementsUtility.cs:68)
UnityEngine.GUIUtility.ProcessEvent (System.Int32 instanceID, System.IntPtr nativeEventPtr) (at C:/buildslave/unity/build/Modules/IMGUI/GUIUtility.cs:179)