Reproduction Steps:
# Open the attached project
# Open Scene SampleScene
# Dock the Project panel next to the Inspector (only one should be visible at any given time, but both should be initialized and available)
# Select the State-Driven Camera while the Inspector is visible
# Switch to the Project window
# Create a new Animator Controller (RMB in Project view > Animator Controller)
# Open it and create a new animation state
# Click on various objects in the Hierarchy

Expected result: no errors

Actual result:

NullReferenceException: SerializedObject of SerializedProperty has been Disposed.
UnityEditor.SerializedProperty.get_intValue () (at /home/bokken/build/output/unity/unity/Editor/Mono/SerializedProperty.bindings.cs:1010)
Unity.Cinemachine.Editor.CinemachineStateDrivenCameraEditor+<>c__DisplayClass10_0.<CreateInspectorGUI>b__6 () (at ./Library/PackageCache/com.unity.cinemachine@3.0.0-pre.7/Editor/Editors/CinemachineStateDrivenCameraEditor.cs:63)
Unity.Cinemachine.Editor.InspectorUtility.<.cctor>g__OnUserDidSomething|1_0 () (at ./Library/PackageCache/com.unity.cinemachine@3.0.0-pre.7/Editor/Utility/InspectorUtility.cs:31)
UnityEditor.Selection.Internal_CallSelectionChanged () (at /home/bokken/build/output/unity/unity/Editor/Mono/Selection.cs:38)