Verifier: Add check for DICompositeType elements being null
Came up recently with some nodebug case on codeview, that caused a null
entry in elements and crashed LLVM.
Original clang fix to avoid generating IR like this: 504dd577675e8c85cdc8525990a7c8b517a38a89
llvm-project
2dc5682d - Verifier: Add check for DICompositeType elements being null
