Crash when opening or editing a DataTable with a Row Structure that contains a BodyInstance

If a DataTable Asset is created with a Row Structure that contains a member variable of type BodyInstance, the Editor will crash when attempting to open it while it has no rows. It will also crash when editing a populated DataTable and deselecting all rows.

The crash happens at [Engine\Source\Editor\DetailCustomizations\Private\BodyInstanceCustomization.cpp:218], in function FBodyInstanceCustomization::CustomizeChildren(). When no rows are selected in the DataTable Editor, detail customizations such as this should be able to handle IPropertyHandle::AccessRawData() returning an array containing a nullptr. Several other customizations simply skip all work when this happens, but this one calls check() on the pointers, causing the crash.

Test 1:

• Open The Editor on any map
• Create a Structure Asset and add a variable of type BodyInstance
• Create a DataTable Asset and pick the structure above for the rows
• Save both assets before continuing
• Open the DataTable Asset. The Editor will crash.

Test 2:

• Open The Editor on any map
• Create a Structure Asset and leave it with the default boolean variable only
• Create a DataTable Asset and pick the structure above for the rows
• Open the DataTable Asset, create some rows, and select one of them
• Edit the Structure Asset, add a variable of type BodyInstance
• Edit the DataTable Asset, deselect all rows. The Editor will crash.