Simplify handler

Simplify Handler type since eventName can be a string

Author: chris-pardy

types/index.d.ts

@@ -51,9 +51,7 @@ export class Engine {
   removeFact(factOrId: string | Fact): boolean;
   getFact<T>(factId: string): Fact<T>;
 
-  on(eventName: "success", handler: EventHandler): this;
-  on(eventName: "failure", handler: EventHandler): this;
-  on<T>(eventName: string, handler: EventHandler<T>): this;
+  on<T = Event>(eventName: string, handler: EventHandler<T>): this;
 
   run(facts?: Record<string, any>, runOptions?: RunOptions): Promise<EngineResult>;
   stop(): this;