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 `FurnaceExtractEvent`. It only accepts `Event::FurnaceExtractEvent(data)`; any other variant means the dispatcher delivered a mismatched event payload to this handler. The library treats that as an internal invariant violation and panics with "unexpected event".

Solutions

1. Register the handler with `EventType::FurnaceExtractEvent` and confirm dispatch routes only that variant.
2. Build the event via `FurnaceExtractEvent::data_into_event(data)` before manual extraction.
3. Align plugin-api versions across the workspace and rebuild cleanly.
4. Pre-narrow: `if let Event::FurnaceExtractEvent(data) = event { ... }`.
5. Return `None`/log the mismatch instead of panicking.

Example fix

// before
match event {
    Event::FurnaceExtractEvent(data) => data,
    _ => panic!("unexpected event"),
}
// after
match event {
    Event::FurnaceExtractEvent(data) => data,
    _ => return None,
}

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

fn as_furnace_extract(event: &Event) -> Option<&FurnaceExtractEventData> {
    match event {
        Event::FurnaceExtractEvent(data) => Some(data),
        _ => None,
    }
}

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

When it happens

Trigger: Passing an `Event` other than `Event::FurnaceExtractEvent` into `data_from_event`, e.g. other furnace or inventory events routed to this handler, or registration under the wrong `EventType`.

Common situations: Mixing up furnace event handlers (burn/smelt/extract) in registration tables, custom dispatch code, or version skew where the `Event` enum differs between server and plugin.

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/7a993ad0e631f37e. Report an issue: GitHub.

Appendix: source

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

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

/// Event triggered when a player extracts items from a furnace output slot.
pub struct FurnaceExtractEvent;
impl FromIntoEvent for FurnaceExtractEvent {
    const EVENT_TYPE: EventType = EventType::FurnaceExtractEvent;
    type Data = FurnaceExtractEventData;

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

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

View on GitHub (pinned to 8d4639e25a)