Elementplus遇到的问题

问题1：
el-upload 手动上传图片，，上传之后，，el-upload 中插槽的图片无法显示，，，官网也是无法显示
- 手动上传图片，，，返回图片的url，，然后在上传表单

  <el-form-item label="图片" prop="imgUrl"  >
        <img v-if="form.imgUrl" :src="form.imgUrl" class="avatar"/>
        <el-upload :before-upload="handleBeforeUpload" action="#" list-type="picture-card" :auto-upload="true" :limit="1" :on-exceed="handleExceed" ref="upload">
          <img v-if="false" src="#" class="avatar" />
          <el-icon v-else class="avatar-uploader-icon"><Plus /></el-icon>
        </el-upload>
      </el-form-item>

const uploadFile = (file)=>{
  var formData = new FormData();
  formData.append("file",file)
  return http.post("/upload",formData,{
    headers:{
      "Content-Type":"multipart/form-data"
    }
  })
}
let imgUrl = ref("")
const handleBeforeUpload = async (file) => {
  console.log(file)
  if (file.type !== "image/jpeg" && file.type !== "image/png") {
    ElMessage.error("图片格式不对")
    return false
  } else if (file.size / 1024 / 1024 > 5) {
    ElMessage.error("太大")
    return false;
  }


  let {data: res} = await uploadFile(file)


  form.imgUrl = res

  // 阻止默认上传
  return false
}