-NullReferenceException errors are thrown continuously when the main camera stack is assigned with an overlay camera and reset "Universal Additional Camera Data" component of Overlay Camera.
-ArgumentException error is thrown on resetting "Universal Additional Camera Data" component from Overlay Camera.

Steps to repro:
1. Create a new URP Template Project.
2. Create a new Camera > Change its Render Mode to Overlay
3. Select Main Camera > Assign Stack Camera.
4. Select Camera > reset "Universal Additional Camera Data" component.

Actual Result:
ArgumentException and NullReferenceException errors are thrown in the console.

Expected Result:
No error in the console.

Reproducible in:
2020.2.0a7, 2020.1.0b6, 2019.3.0f6 with Package Version: 9.0.0, 8.0.1, 7.3.1, 7.2.1, 7.2.0.

Note: Overlay Render type is introduced in Package Version: 7.2.0

Environment:
Occurring on Windows 10 & Mac 10.15.

Stack trace:
ArgumentException: Getting control 25's position in a group with only 25 controls when doing repaint
Aborting
UnityEngine.GUILayoutGroup.GetNext () (at <7e072e4699014d9089b4f15a2244620f>:0)
UnityEngine.GUILayoutUtility.DoGetRect (UnityEngine.GUIContent content, UnityEngine.GUIStyle style, UnityEngine.GUILayoutOption[] options) (at <7e072e4699014d9089b4f15a2244620f>:0)
UnityEngine.GUILayoutUtility.GetRect (UnityEngine.GUIContent content, UnityEngine.GUIStyle style) (at <7e072e4699014d9089b4f15a2244620f>:0)
UnityEditor.EditorGUILayout.BeginFoldoutHeaderGroup (System.Boolean foldout, UnityEngine.GUIContent content, UnityEngine.GUIStyle style, System.Action`1[T] menuAction, UnityEngine.GUIStyle menuIcon) (at <b0707acaff7743ddbcba0f9c9b5c49cc>:0)
UnityEditor.Rendering.Universal.UniversalRenderPipelineCameraEditor.DrawEnvironmentSettings (UnityEngine.Rendering.Universal.CameraRenderType camType) (at library/packagecache/com.unity.render-pipelines.universal@9.0.0-preview.14/editor/universalrenderpipelinecameraeditor.cs:528)
UnityEditor.Rendering.Universal.UniversalRenderPipelineCameraEditor.OnInspectorGUI () (at library/packagecache/com.unity.render-pipelines.universal@9.0.0-preview.14/editor/universalrenderpipelinecameraeditor.cs:452)
UnityEditor.UIElements.InspectorElement+<>c__DisplayClass58_0.<CreateIMGUIInspectorFromEditor>b__0 () (at <b0707acaff7743ddbcba0f9c9b5c49cc>:0)
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr, Boolean&)

NullReferenceException: Object reference not set to an instance of an object
UnityEditor.Rendering.Universal.UniversalRenderPipelineCameraEditor.DrawStackSettings () (at library/packagecache/com.unity.render-pipelines.universal@9.0.0-preview.14/editor/universalrenderpipelinecameraeditor.cs:501)
UnityEditor.Rendering.Universal.UniversalRenderPipelineCameraEditor.OnInspectorGUI () (at library/packagecache/com.unity.render-pipelines.universal@9.0.0-preview.14/editor/universalrenderpipelinecameraeditor.cs:458)
UnityEditor.UIElements.InspectorElement+<>c__DisplayClass58_0.<CreateIMGUIInspectorFromEditor>b__0 () (at <b0707acaff7743ddbcba0f9c9b5c49cc>:0)
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr, Boolean&)