Function parse_ticker_linear_index_price 

pub fn parse_ticker_linear_index_price(
    data: &BybitWsTickerLinear,
    instrument: &InstrumentAny,
    ts_event: UnixNanos,
    ts_init: UnixNanos,
) -> Result<IndexPriceUpdate>

Parses a linear/inverse ticker payload into an [IndexPriceUpdate].

Errors

Returns an error if the index_price field is missing or cannot be parsed.