Mystery crash ZipFile::createStreamForEntry

I’ve been pulling audio files out of a downloaded zip file. I’m now also bundling some of the audio files as a zip file in BinaryData.

To pull the zip file from BinaryData I’m doing:

                // Load from binary data
                MemoryBlock mb (BinaryData::freewordaudio_zip, BinaryData::freewordaudio_zipSize);
                MemoryInputStream inputStream (mb, true);
                audioZipFile = std::make_unique<ZipFile> (&inputStream, true);

(audioZipFile is now a std::unique_ptr class member`)

and after some checks I’m then reading a single file in with:

            auto audioFileName = word[Word::Ids::fileName].toString() + ".mp3";
            auto* zipEntry = audioZipFile->getEntry (audioFileName, false);
            jassert (zipEntry != nullptr);
            if (zipEntry == nullptr)
                return false;

            audioZipFile->createStreamForEntry (*zipEntry)->readIntoMemoryBlock (wordAudioData);

This second part is fine when loading from an actual zip file (not from BinaryData). When loading from BinaryData, it crashes in createStreamForEntry at

        stream = new ZipInputStream (*this, *zei);

where, at the time of the crash, this seems to be NULL. So it looks like something going out of scope. But I can’t work out what…