Function parse_ws_fill_report 

pub fn parse_ws_fill_report(
    exec: &KrakenWsExecutionData,
    instrument: &InstrumentAny,
    account_id: AccountId,
    ts_init: UnixNanos,
) -> Result<FillReport>

Parses a Kraken WebSocket trade execution into a [FillReport].

This should only be called when exec_type is “trade”.

Errors

Returns an error if required fields are missing or cannot be parsed.