public byte readNextByte() throws IOException {
        byte b = readByte(currentIndex);
        currentIndex += SIZEOF_BYTE;
        return b;
    }
Reads the byte at the current index and then increments the current
index by <code>SIZEOF_BYTE</code>.
@return the byte at the current index
@exception IOException if an I/O error occurs
GPL/DMG/src/dmg/java/mobiledevices/dmg/ghidra/GBinaryReader.java