When running hs :tier1 tests, with ubsan enabled (configure flag --enable-ubsan), in test runtime/CommandLine/PrintClasses_id0.jtr
this error is reported ; seems we miss a nullptr check that is in place at similar coding in instanceKlass.cpp .

/jdk/src/hotspot/share/oops/instanceKlass.cpp:3550:76: runtime error: member call on null pointer of type 'struct Array'
    #0 0x7fed098d2362 in InstanceKlass::print_on(outputStream*) const /jdk/src/hotspot/share/oops/instanceKlass.cpp:3550
    #1 0x7fed09897cdc in PrintClassClosure::do_klass(Klass*) /jdk/src/hotspot/share/oops/instanceKlass.cpp:2228
    #2 0x7fed08bed334 in ClassLoaderData::classes_do(KlassClosure*) /jdk/src/hotspot/share/classfile/classLoaderData.cpp:387
    #3 0x7fed08c06403 in ClassLoaderDataGraph::classes_do(KlassClosure*) /jdk/src/hotspot/share/classfile/classLoaderDataGraph.cpp:303
    #4 0x7fed09108768 in VM_PrintClasses::doit() /jdk/src/hotspot/share/services/diagnosticCommand.cpp:989
    #5 0x7fed0b776c38 in VM_Operation::evaluate() /jdk/src/hotspot/share/runtime/vmOperations.cpp:75
    #6 0x7fed0b7af23e in VMThread::evaluate_operation(VM_Operation*) /jdk/src/hotspot/share/runtime/vmThread.cpp:283
    #7 0x7fed0b7b0a67 in VMThread::inner_execute(VM_Operation*) /jdk/src/hotspot/share/runtime/vmThread.cpp:427
    #8 0x7fed0b7b1681 in VMThread::loop() /jdk/src/hotspot/share/runtime/vmThread.cpp:493
    #9 0x7fed0b7b1681 in VMThread::loop() /jdk/src/hotspot/share/runtime/vmThread.cpp:478
    #10 0x7fed0b7b182d in VMThread::run() /jdk/src/hotspot/share/runtime/vmThread.cpp:177
    #11 0x7fed0b4e8b0f in Thread::call_run() /jdk/src/hotspot/share/runtime/thread.cpp:225
    #12 0x7fed0a9dae75 in thread_native_entry /jdk/src/hotspot/os/linux/os_linux.cpp:846
    #13 0x7fed10fed6e9 in start_thread (/lib64/libpthread.so.0+0xa6e9) (BuildId: 2f8d3c2d0f4d7888c2598d2ff6356537f5708a73)
    #14 0x7fed1051550e in clone (/lib64/libc.so.6+0x11850e) (BuildId: f732026552f6adff988b338e92d466bc81a01c37)