@zip.js/zip.js
    Preparing search index...

    Variable ERR_UNDEFINED_CRC32Const

    ERR_UNDEFINED_CRC32: string

    Undefined CRC32 error (thrown by ZipWriter#add when the ZipWriterConstructorOptions#passThrough option is set and the ZipWriterAddDataOptions#crc32 option is unset on an entry which stores a checksum)

    The checksum cannot be computed from data which is not decompressed, and every entry stores one except an AES entry in AE-2 format, so writing the data as-is without declaring it would store a zero which other tools reject. Copying an entry read with the ZipReaderOptions#passThrough option set to "compressed" from an AE-2 source into an entry which is not AES-encrypted is therefore refused rather than written: that source published no checksum to carry over.