When Prefab GameObject is exported and replaced with existing Prefab Asset then it causes the editor to throw ArgumentNullException, Refer attached video.

Steps to repro:
1. Create a new project.
2. Window > Package Manager > ProBuilder > Install
3. Tools > ProBuilder > ProBuilder window > Create a New Shape
4. Darg and drop "New Shape" to Project window for making a Prefab
5. Select a New Shape Prefab in the Hierarchy window
6. ProBuilder window > Export > Prefab > Save and Replaced existed asset

Actual Result:
ArgumentNullException is thrown when the existing Prefab object is exported, saved, and replaced.

Expected Result:
Prefab asset is exported, saved, and replaced gracefully

Occurring on:
2020.2.0b6, 2020.1.7f1, 2019.4.12f1, 2018.4.27f1

Note: Prefab Export functionality is introduced in the Package version 4.0.2

Package found version: 4.4.0, 4.3.1, 4.2.3, 4.2.1, 4.1.0, 4.0.2

Environment:
Occurring on Windows 10 & macOS 10.15.

Stack trace:
ArgumentNullException: Value cannot be null.
Parameter name: mesh
UnityEditor.ProBuilder.EditorUtility.SynchronizeWithMeshFilter (UnityEngine.ProBuilder.ProBuilderMesh mesh) (at Library/PackageCache/com.unity.probuilder@4.4.0/Editor/EditorCore/EditorUtility.cs:193)
UnityEditor.ProBuilder.Actions.ExportAsset.ExportPrefab (System.String path, UnityEngine.ProBuilder.ProBuilderMesh pb, System.Boolean replaceOriginal, System.Boolean batchExport) (at Library/PackageCache/com.unity.probuilder@4.4.0/Editor/MenuActions/Export/ExportAsset.cs:258)
UnityEditor.ProBuilder.Actions.ExportAsset.ExportPrefab (UnityEngine.ProBuilder.ProBuilderMesh mesh, System.Boolean replaceOriginal) (at Library/PackageCache/com.unity.probuilder@4.4.0/Editor/MenuActions/Export/ExportAsset.cs:159)
UnityEditor.ProBuilder.Actions.ExportAsset.ExportWithFileDialog (System.Collections.Generic.IList`1[T] meshes, UnityEditor.ProBuilder.Actions.ExportAssetOptions options) (at Library/PackageCache/com.unity.probuilder@4.4.0/Editor/MenuActions/Export/ExportAsset.cs:75)
UnityEditor.ProBuilder.Actions.Export.DoAction () (at Library/PackageCache/com.unity.probuilder@4.4.0/Editor/MenuActions/Export/Export.cs:211)
UnityEditor.ProBuilder.Actions.Export.OnSettingsGUI () (at Library/PackageCache/com.unity.probuilder@4.4.0/Editor/MenuActions/Export/Export.cs:124)
UnityEditor.ProBuilder.MenuOption.OnGUI () (at Library/PackageCache/com.unity.probuilder@4.4.0/Editor/EditorCore/MenuOption.cs:78)
UnityEditor.HostView.OldOnGUI () (at <3f87d5057260449492001887e23ef996>:0)
UnityEngine.UIElements.IMGUIContainer.DoOnGUI (UnityEngine.Event evt, UnityEngine.Matrix4x4 parentTransform, UnityEngine.Rect clippingRect, System.Boolean isComputingLayout, UnityEngine.Rect layoutSize, System.Action onGUIHandler, System.Boolean canAffectFocus) (at <17eda2bc62404501b9f55a9eba6f522e>:0)
UnityEngine.UIElements.IMGUIContainer.HandleIMGUIEvent (UnityEngine.Event e, UnityEngine.Matrix4x4 worldTransform, UnityEngine.Rect clippingRect, System.Action onGUIHandler, System.Boolean canAffectFocus) (at <17eda2bc62404501b9f55a9eba6f522e>:0)
UnityEngine.UIElements.IMGUIContainer.HandleIMGUIEvent (UnityEngine.Event e, System.Action onGUIHandler, System.Boolean canAffectFocus) (at <17eda2bc62404501b9f55a9eba6f522e>:0)
UnityEngine.UIElements.IMGUIContainer.HandleIMGUIEvent (UnityEngine.Event e, System.Boolean canAffectFocus) (at <17eda2bc62404501b9f55a9eba6f522e>:0)
UnityEngine.UIElements.IMGUIContainer.SendEventToIMGUIRaw (UnityEngine.UIElements.EventBase evt, System.Boolean canAffectFocus, System.Boolean verifyBounds) (at <17eda2bc62404501b9f55a9eba6f522e>:0)
UnityEngine.UIElements.IMGUIContainer.SendEventToIMGUI (UnityEngine.UIElements.EventBase evt, System.Boolean canAffectFocus, System.Boolean verifyBounds) (at <17eda2bc62404501b9f55a9eba6f522e>:0)
UnityEngine.UIElements.IMGUIContainer.HandleEvent (UnityEngine.UIElements.EventBase evt) (at <17eda2bc62404501b9f55a9eba6f522e>:0)
UnityEngine.UIElements.CallbackEventHandler.HandleEventAtTargetPhase (UnityEngine.UIElements.EventBase evt) (at <17eda2bc62404501b9f55a9eba6f522e>:0)
UnityEngine.UIElements.MouseCaptureDispatchingStrategy.DispatchEvent (UnityEngine.UIElements.EventBase evt, UnityEngine.UIElements.IPanel panel) (at <17eda2bc62404501b9f55a9eba6f522e>:0)
UnityEngine.UIElements.EventDispatcher.ApplyDispatchingStrategies (UnityEngine.UIElements.EventBase evt, UnityEngine.UIElements.IPanel panel, System.Boolean imguiEventIsInitiallyUsed) (at <17eda2bc62404501b9f55a9eba6f522e>:0)
UnityEngine.UIElements.EventDispatcher.ProcessEvent (UnityEngine.UIElements.EventBase evt, UnityEngine.UIElements.IPanel panel) (at <17eda2bc62404501b9f55a9eba6f522e>:0)
UnityEngine.UIElements.EventDispatcher.ProcessEventQueue () (at <17eda2bc62404501b9f55a9eba6f522e>:0)
UnityEngine.UIElements.EventDispatcher.OpenGate () (at <17eda2bc62404501b9f55a9eba6f522e>:0)
UnityEngine.UIElements.EventDispatcherGate.Dispose () (at <17eda2bc62404501b9f55a9eba6f522e>:0)
UnityEngine.UIElements.EventDispatcher.ProcessEvent (UnityEngine.UIElements.EventBase evt, UnityEngine.UIElements.IPanel panel) (at <17eda2bc62404501b9f55a9eba6f522e>:0)
UnityEngine.UIElements.EventDispatcher.Dispatch (UnityEngine.UIElements.EventBase evt, UnityEngine.UIElements.IPanel panel, UnityEngine.UIElements.DispatchMode dispatchMode) (at <17eda2bc62404501b9f55a9eba6f522e>:0)
UnityEngine.UIElements.BaseVisualElementPanel.SendEvent (UnityEngine.UIElements.EventBase e, UnityEngine.UIElements.DispatchMode dispatchMode) (at <17eda2bc62404501b9f55a9eba6f522e>:0)
UnityEngine.UIElements.UIElementsUtility.DoDispatch (UnityEngine.UIElements.BaseVisualElementPanel panel) (at <17eda2bc62404501b9f55a9eba6f522e>:0)
UnityEngine.UIElements.UIElementsUtility.UnityEngine.UIElements.IUIElementsUtility.ProcessEvent (System.Int32 instanceID, System.IntPtr nativeEventPtr, System.Boolean& eventHandled) (at <17eda2bc62404501b9f55a9eba6f522e>:0)
UnityEngine.UIElements.UIEventRegistration.ProcessEvent (System.Int32 instanceID, System.IntPtr nativeEventPtr) (at <17eda2bc62404501b9f55a9eba6f522e>:0)
UnityEngine.UIElements.UIEventRegistration+<>c.<.cctor>b__1_2 (System.Int32 i, System.IntPtr ptr) (at <17eda2bc62404501b9f55a9eba6f522e>:0)
UnityEngine.GUIUtility.ProcessEvent (System.Int32 instanceID, System.IntPtr nativeEventPtr, System.Boolean& result) (at <931b26b61f444e3485195721b0227b20>:0)