Exploring the Concept of a `TaggedError` for Library APIs

export const TaggedError = <Key extends string>(tag: Key) => 
    class CustomError<Meta extends object = never> extends Error {
        readonly _tag = tag
        readonly metadata: Meta
        constructor(...[message, meta]: ErrorArgs<Meta>) {
            const details = !meta ? '' : '\n' + JSON.stringify(meta, null, 2)
            super(message + details);
            this.name = this._tag;
            this.metadata = meta || {} as any
        }
    }

type ErrorArgs<T> =
    [T] extends [never]
    ? [message: string]
    : [message: string, metadata: T];

export const unwrapEffect = <Args extends any[], R>(f: EffectfulFn<Args, R>) =>
    (...args: Args): R => pipe(
        f(...args),
        Effect.either,
        Effect.runSync,
        E.match({
            onLeft: error => { throw error; },
            onRight: identity
        })
    );

type EffectfulFn<Args extends any[], R> =
    (...args: Args) => Effect.Effect<never, unknown, R>