function readH3IndexFromPointer(cAddress, offset = 0) {
    const lower = C.getValue(cAddress + SZ_H3INDEX * offset, 'i32');
    const upper = C.getValue(cAddress + SZ_H3INDEX * offset + SZ_INT, 'i32');
    // The lower bits are allowed to be 0s, but if the upper bits are 0
    // this represents an invalid H3 index
    return upper ? splitLongToH3Index(lower, upper) : null;
}
Read an H3 index from a pointer to C memory.
@private
@param  {number} cAddress  Pointer to allocated C memory
@param {number} offset     Offset, in number of H3 indexes, in case we're
                           reading an array
@return {H3Index | null}   H3 index, or null if index was invalid