data数据返回报异常的问题？

代码如下：

if (res.code === 0) {
        if (res.data.agreementUrl) {
          this.arrItems = (res.data.agreementUrl || "").split(",");
          const params = this.arrItems.map((val) => {
            return { url: val };
          });
          this.fileList = params;
        }
      }

点击按钮报了这个异常：

CommuniterImg.vue?2e9a:74 Uncaught (in promise) TypeError: Cannot read properties of null (reading 'agreementUrl')

那怎么解决这个问题呢