State 'task3' already has a next state

samplestack.ts

import cdk = require("@aws-cdk/core");
import sfn = require("@aws-cdk/aws-stepfunctions");
import { Duration } from "@aws-cdk/core";

export class SampleStack extends cdk.Stack {
    constructor(app: cdk.App, id: string, props?: cdk.StackProps) {
        super(app, id, props);

        const task1 = new sfn.Wait(this, "task1", {
            time: sfn.WaitTime.duration(Duration.minutes(1)),
        });

        const task2 = new sfn.Wait(this, "task2", {
            time: sfn.WaitTime.duration(Duration.seconds(60 / 4)),
        });

        const task3 = new sfn.Wait(this, "task3", {
            time: sfn.WaitTime.duration(Duration.seconds(60 / 4)),
        });

        const task4 = new sfn.Choice(this, "task4");
        const cond1 = sfn.Condition.booleanEquals("$.hoge", true);
        const cond2 = sfn.Condition.booleanEquals("$.fuga", true);

        const task5 = new sfn.Wait(this, "task5", {
            time: sfn.WaitTime.duration(Duration.seconds(5)),
        });

        const task6 = new sfn.Wait(this, "task6", {
            time: sfn.WaitTime.duration(Duration.seconds(5)),
        });

        const task7 = new sfn.Wait(this, "task7", {
            time: sfn.WaitTime.duration(Duration.seconds(5)),
        });

        new sfn.StateMachine(this, "machine1", {
            definition: task1
                .next(task2)
                .next(task3)
                .next(
                    task4
                        .when(cond1, task2)
                        .when(cond2, task5)
                        .otherwise(task6)
                        .afterwards()
                )
                .next(task7),
        });
    }
}