feat: add error event

README.md

@@ -80,6 +80,32 @@ remitter.emit("event1", "hello"); // logs "event1 hello"
 remitter.emit("event2", "world"); // logs "event2 world"
 ```
 
+### Listen to unhandled subscriber errors
+
+```ts
+import { Remitter } from "remitter";
+
+interface EventData {
+  event1: string;
+  event2: string;
+}
+
+const remitter = new Remitter<EventData>();
+
+remitter.onError(error => {
+  console.log(error);
+});
+
+remitter.emit("event1", () => {
+  throw new Error("error");
+});
+
+remitter.emit("event2", async () => {
+  await new Promise(resolve => setTimeout(resolve, 100));
+  throw new Error("async-error");
+});
+```
+
 ### Remit
 
 You may tap into other events easily with `remit`. It is lazy-executed when listener count of the event name grows from 0 to 1. It is disposed when listener count of the event name drops from 1 to 0.

src/constants.ts

@@ -4,3 +4,10 @@
 export const ANY_EVENT = /* @__PURE__ */ Symbol();
 
 export type ANY_EVENT = typeof ANY_EVENT;
+
+/**
+ * A symbol that can be used as an event name to listen to unhandled subscriber errors.
+ */
+export const ERROR_EVENT = /* @__PURE__ */ Symbol();
+
+export type ERROR_EVENT = typeof ERROR_EVENT;

src/interface.ts

@@ -1,4 +1,4 @@
-import type { ANY_EVENT } from "./constants";
+import type { ANY_EVENT, ERROR_EVENT } from "./constants";
 
 export type Fn = (...args: any[]) => any;
 
@@ -13,6 +13,8 @@ export type AnyRemitterListener<TConfig> = (
   data: AnyEventData<TConfig>
 ) => void;
 
+export type ErrorRemitterListener = (error: unknown) => void;
+
 export type RemitterConfig<TConfig> = TConfig & {
   [name in ANY_EVENT]: AnyEventData<TConfig>;
 };
@@ -28,7 +30,10 @@ export type RemitterDatalessEventName<TConfig> = {
 
 export type RemitterEventNames<TConfig> = keyof TConfig;
 
-export type AllRemitterEventNames<TConfig> = keyof TConfig | ANY_EVENT;
+export type AllRemitterEventNames<TConfig> =
+  | keyof TConfig
+  | ANY_EVENT
+  | ERROR_EVENT;
 
 export type RemitterListener<
   TConfig,