Definition of an execution unit that can fail

canFail.ts

class CanFail implements ExecutionUnit {
    next: ExecutionUnit | null;
    pipeline: IAPPipeline;
    constructor(pipeline: IAPPipeline) {
      this.next = null;
      this.pipeline = pipeline;
    }
    setNext(next: ExecutionUnit): void {
      this.next = next;
    }
    async exec(req: Request, res: Response): Promise<void | never> {
      try {
        await this.pipeline(req, res);
      } catch (e) {
        console.error(e);
        if (this.next !== null) {
          await this.next.exec(req, res);
        }
      }
    }
  }