Uninitialized scalar field
The field will contain an arbitrary value left over from earlier computations. A scalar field is not initialized by the constructor
/src/mongo/db/catalog/collection.h:655: UNINIT_CTOR 116380 Class member declaration for "_catalogEpoch".
/src/mongo/db/catalog/collection.cpp:84: UNINIT_CTOR 116380 Non-static class member "_catalogEpoch" is not initialized in this constructor nor in any functions that it calls.