Pumpkin-MC/Pumpkin · error

unexpected event

Error message

unexpected event

What it means

This panic fires in `data_from_event`, the `Event` trait implementation for `FurnaceBurnEvent`. It extracts data only from `Event::FurnaceBurnEvent(data)`; any other `Event` variant indicates the dispatcher sent the wrong event type to the furnace-burn handler. The library treats the mismatch as an invariant break and panics with "unexpected event".

Solutions

1. Register the handler for `EventType::FurnaceBurnEvent` so only that variant is dispatched to it.
2. Use `FurnaceBurnEvent::data_into_event(data)` when constructing the event for manual calls.
3. Synchronize pumpkin-plugin-api versions and clean-rebuild to fix enum mismatches.
4. Check the variant before calling: `if let Event::FurnaceBurnEvent(data) = event { ... }`.
5. Swap the panic for a logged error or `Result` return to avoid crashing the server.

Example fix

// before
match event {
    Event::FurnaceBurnEvent(data) => data,
    _ => panic!("unexpected event"),
}
// after
match event {
    Event::FurnaceBurnEvent(data) => data,
    _ => return Err(EventDispatchError::UnexpectedVariant),
}

// Before dispatch
assert_eq!(event.event_type(), EventType::FurnaceBurnEvent, "wrong event routed to FurnaceBurn handler");

fn as_furnace_burn(event: &Event) -> Option<&FurnaceBurnEventData> {
    match event {
        Event::FurnaceBurnEvent(data) => Some(data),
        _ => None,
    }
}

let result = std::panic::catch_unwind(AssertUnwindSafe(|| handler.data_from_event(event)));
if result.is_err() {
    log::error!("FurnaceBurnEvent handler received an unexpected event variant");
}

When it happens

Trigger: Calling `data_from_event` with a non-`FurnaceBurnEvent` variant — e.g. furnace smelt/extract events routed here — or a handler registration keyed to the wrong `EventType`.

Common situations: Copy-paste handler registration that mixes furnace event types, custom dispatch logic, or `Event` enum drift between server and plugin versions after an upgrade.

Understand the failure class

Background: "This is a bug, please report it": internal invariant violations, unreachable panics, and SNH errors explained — this error's family across 47 libraries.

Related errors

• unexpected event
• unexpected event
• unexpected event
• unexpected event
• unexpected event

AI-assisted analysis of Pumpkin-MC/Pumpkin@8d4639e25a (2026-09-09). Data as JSON: /api/errors/a2b45c6594d45cf9. Report an issue: GitHub.

Appendix: source

Thrown at crates/pumpkin-plugin-api/src/events/inventory/furnace_burn.rs:13

use super::super::FromIntoEvent;
use crate::wit::pumpkin::plugin::event::{Event, EventType, FurnaceBurnEventData};

/// Event triggered when fuel is burned in a furnace.
pub struct FurnaceBurnEvent;
impl FromIntoEvent for FurnaceBurnEvent {
    const EVENT_TYPE: EventType = EventType::FurnaceBurnEvent;
    type Data = FurnaceBurnEventData;

    fn data_from_event(event: Event) -> Self::Data {
        match event {
            Event::FurnaceBurnEvent(data) => data,
            _ => panic!("unexpected event"),
        }
    }

    fn data_into_event(data: Self::Data) -> Event {
        Event::FurnaceBurnEvent(data)
    }
}

View on GitHub (pinned to 8d4639e25a)