nautechsystems/nautilus_trader · error

Failed to build BybitRepayParams

Error message

Failed to build BybitRepayParams

What it means

`repay` builds `BybitRepayParams` and unwraps `build()` with `expect`. derive_builder's `build()` fails only on missing required fields, so the panic means a non-optional field of `BybitRepayParams` was never set on the builder — an internal invariant treated as unrecoverable.

Source

Thrown at crates/adapters/bybit/src/http/client.rs:1482

    /// # References
    ///
    /// - <https://bybit-exchange.github.io/docs/v5/account/repay>
    pub async fn repay(
        &self,
        coin: Option<&str>,
        amount: Option<&str>,
    ) -> Result<BybitRepayResponse, BybitHttpError> {
        let mut builder = BybitRepayParamsBuilder::default();

        if let Some(coin) = coin {
            builder.coin(coin.to_string());
        }

        if let Some(amt) = amount {
            builder.amount(amt.to_string());
        }

        let params = builder.build().expect("Failed to build BybitRepayParams");

        if let Ok(params_json) = serde_json::to_string(&params) {
            log::debug!("Repay request params: {params_json}");
        }

        let body = serde_json::to_vec(&params)?;
        let result = self
            .send_request::<_, ()>(Method::POST, "/v5/account/repay", None, Some(body), true)
            .await;

        if let Err(ref e) = result
            && let Ok(params_json) = serde_json::to_string(&params)
        {
            log::error!("Repay request failed with params {params_json}: {e}");
        }

        result
    }

View on GitHub (pinned to 18893faf8b)

Solutions

  1. Set every non-Option field on the builder before `.build()`
  2. Convert the `expect` into `?` mapping to `BybitHttpError`
  3. Re-check the builder chain after crate or Bybit API upgrades
  4. File a bug if it panics via the public `repay` call

Example fix

// before
let params = builder.build().expect("Failed to build BybitRepayParams");
// after
let params = builder.build().map_err(BybitHttpError::InvalidParams)?;
Defensive patterns

Strategy: validation

Validate before calling

// Validate required repay fields before the call
assert!(!coin.is_empty(), "coin is required");
if let Some(a) = amount { assert!(a.parse::<Decimal>().map(|d| d > Decimal::ZERO).unwrap_or(false), "amount must be positive"); }

Try / catch

match client.repay(coin, amount).await { Err(e) => { log::error!("repay: {e}"); Err(e.into()) }, Ok(r) => Ok(r) }

Prevention

When it happens

Trigger: A required field of `BybitRepayParams` missing from the builder chain (e.g. coin not set after refactoring the conditional setters), or the struct gains a new mandatory field on a Bybit API update.

Common situations: Custom repay flows building params manually; schema drift after upgrades; merge conflicts removing a setter call.

Understand the failure class

Background: "missing required argument" and "the following required arguments were not provided": what required-argument errors mean and how to fix them — this error's family across 20 libraries.

Related errors

AI-assisted analysis of nautechsystems/nautilus_trader@18893faf8b (2026-09-08). Data as JSON: /api/errors/186504e71d8e5567. Report an issue: GitHub.