mybatis-plus报错java.lang.NullPointerException

Question

问题遇到的现象和发生背景

mybatis-plus写自定义的sql的时候报错，跟着视频的代码敲，视频里面没有报错，自己的报错了

用代码块功能插入代码，请勿粘贴截图

MainApplication.java

package org.example.smile;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@MapperScan("org.example.smile.mapper")
@SpringBootApplication
public class MainApplication {
    public static void main(String[] args) {
        SpringApplication.run(MainApplication.class,args);
    }
}

application.yml

server:
  port: 8888
spring:
  datasource:
    type: com.zaxxer.hikari.HikariDataSource
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/hd?serverTimezone=GMT&useUnicode=true&characterEncoding=utf-8&useSSL=false
    username: root
    password: root
mybatis-plus:
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl

NewsMapper.java

package org.example.smile.mapper;

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import org.example.smile.pojo.News;
import org.springframework.stereotype.Repository;

@Repository
public interface NewsMapper extends BaseMapper<News> {
    News getNewsById();
}

NewsMapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="org.example.smile.mapper.NewsMapper">
    <select id="getNewsById" resultType="News">
        select * from hd_news
    </select>
</mapper>

运行结果及报错内容

我的解答思路和尝试过的方法

总感觉是mapper.xml那一块出了问题，但怎么都找不到问题出在哪，我知道有一个叫mapper-locations扫描xml的配置，但视频里默认没写，默认不写的时候就是在resources下创一个mapper路径就可以扫描了

我想要达到的结果

让mybatis-plus可以自己自定义sql语句