Seen on crash-stats.

Crash report: https://crash-stats.mozilla.org/report/index/e41b6984-237e-4696-8c11-d05500220531

MOZ_CRASH Reason: MOZ_DIAGNOSTIC_ASSERT(mAllocatedImages.IsEmpty()) (Should release all shmem buffers before destroy!)

Top 10 frames of crashing thread:

0 libxul.so mozilla::FFmpegVideoDecoder<59>::~FFmpegVideoDecoder dom/media/platforms/ffmpeg/FFmpegVideoDecoder.cpp:412
1 libxul.so mozilla::FFmpegVideoDecoder<59>::~FFmpegVideoDecoder dom/media/platforms/ffmpeg/FFmpegVideoDecoder.cpp:410
2 libxul.so mozilla::MozPromise<bool, bool, false>::ThenValue<mozilla::MediaDataDecoderProxy::Shutdown xpcom/threads/MozPromise.h:914
3 libxul.so mozilla::MozPromise<bool, bool, false>::ThenValueBase::ResolveOrRejectRunnable::Run xpcom/threads/MozPromise.h:487
4 libxul.so mozilla::TaskQueue::Runner::Run xpcom/threads/TaskQueue.cpp:259
5 libxul.so nsThreadPool::Run xpcom/threads/nsThreadPool.cpp:310
6 libxul.so nsThread::ProcessNextEvent xpcom/threads/nsThread.cpp:1174
7 libxul.so mozilla::ipc::MessagePumpForNonMainThreads::Run ipc/glue/MessagePump.cpp:300
8 libxul.so MessageLoop::Run ipc/chromium/src/base/message_loop.cc:355
9 libxul.so nsThread::ThreadFunc xpcom/threads/nsThread.cpp:378