Pumpkin-MC/Pumpkin · error

unexpected event type

Error message

unexpected event type

What it means

The EntityRegainHealthEvent from-conversion panics "unexpected event type" when the WIT Event it receives is not Event::EntityRegainHealthEvent. Each event converter handles exactly one variant, and the catch-all arm exists only to exhaust the match; reaching it means the host dispatcher routed the wrong event into this converter. The panic aborts the plugin host.

Solutions

1. Regenerate WIT bindings and the event dispatch so each variant maps to its converter
2. Synchronize Pumpkin host and pumpkin plugin API versions
3. Audit newly added Event variants for missing converter/dispatch registration
4. In a fork, return an error and skip the event instead of panicking

Example fix

// before
_ => panic!("unexpected event type"),
// after
other => {
    log::error!("EntityRegainHealthEvent converter got unexpected event: {other:?}");
    return Err("unexpected event type".into());
}

assert!(matches!(event, Event::EntityRegainHealthEvent(_)), "converter/dispatch mismatch for EntityRegainHealthEvent");

fn is_regain_health(e: &Event) -> bool {
    matches!(e, Event::EntityRegainHealthEvent(_))
}

let result = std::panic::catch_unwind(|| dispatch_to_plugins(event));
if result.is_err() { log::error!("plugin host panicked converting EntityRegainHealthEvent"); }

When it happens

Trigger: The WASM event deserialization layer (from_wasm_event) delivers any Event variant other than EntityRegainHealthEvent to this converter — normally only possible if the dispatch table is stale or the Event enum changed without regenerating glue.

Common situations: Adding new entity event variants without updating dispatch; mismatched plugin-API and host versions; macro-generated converters out of sync with the handwritten WIT enum.

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

• Cannot construct BlockReceiveGameEvent from WASM
• failed to add item stack resource
• Cannot construct BlockShearEntityEvent from WASM
• Cannot construct CrafterCraftEvent from WASM
• Cannot construct EntityBlockFormEvent from WASM

AI-assisted analysis of Pumpkin-MC/Pumpkin@8d4639e25a (2026-09-09). Data as JSON: /api/errors/1c1ad48f81efe272. Report an issue: GitHub.

Appendix: source

Thrown at crates/pumpkin/src/plugin/loader/wasm/wasm_host/wit/v0_1/events/entity.rs:258

}

impl ToFromWasmEvent for EntityRegainHealthEvent {
    fn to_wasm_event(&self, _state: &mut PluginHostState) -> Event {
        Event::EntityRegainHealthEvent(EntityRegainHealthEventData {
            entity_id: self.entity_id,
            amount: self.amount,
            cancelled: self.cancelled,
        })
    }

    fn from_wasm_event(event: Event, _state: &mut PluginHostState) -> Self {
        match event {
            Event::EntityRegainHealthEvent(data) => Self {
                entity_id: data.entity_id,
                amount: data.amount,
                cancelled: data.cancelled,
            },
            _ => panic!("unexpected event type"),
        }
    }
}

impl ToFromWasmEvent
    for crate::plugin::api::events::entity::entity_air_change::EntityAirChangeEvent
{
    fn to_wasm_event(&self, _state: &mut PluginHostState) -> Event {
        Event::EntityAirChangeEvent(EntityAirChangeEventData {
            entity_id: self.entity_id,
            amount: self.amount,
            cancelled: self.cancelled,
        })
    }

    fn from_wasm_event(event: Event, _state: &mut PluginHostState) -> Self {
        match event {
            Event::EntityAirChangeEvent(data) => Self {

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