网页报错：Cannot read properties of undefined (reading 'name')

选择已在库中的时候可以提交，选择未在库中就会报Cannot read properties of undefined (reading 'name')，请问应该怎么修改呢？

class="grid-content bg-purple">
                    
                    <el-radio border size="mini" @change="existenceChange(existence)" v-model="existence" :label="1">
                      已在库中
                    el-radio>
                    <el-radio border size="mini" @change="existenceChange(existence)" v-model="existence" :label="0">
                      未在库中
                    el-radio>
                  

<el-row>
                <el-col :span="8">
                  <el-form-item label="物资数量" prop="numbers" v-show="existence === 1">
                    <el-input v-model="addForm.numbers">el-input>
                  el-form-item>
                el-col>
              el-row>

              

                <el-row>
                  <el-col :span="8">
                    <el-form-item label="物资名称" prop="itemname" v-show="existence === 0">
                      <el-input v-model="addForm.itemname">el-input>
                    el-form-item>
                  el-col>
                el-row>

                <el-row>
                  <el-col :span="8">
                    <el-form-item label="物资数量" prop="numbers" v-show="existence === 0">
                      <el-input v-model="addForm.numbers">el-input>
                    el-form-item>
                  el-col>
                el-row>

                <el-row>
                  <el-col :span="8">
                    <el-form-item label="物资单位" prop="unit" v-show="existence === 0">
                      <el-input v-model="addForm.unit">el-input>
                    el-form-item>
                  el-col>
                el-row>

selectedItems() {
      return this.stockList.filter(item => this.$refs.table.selection.includes(item))
          .map(item => ({ name: item.itemname, unit: item.unit }));
    }

addIn() {
      this.$refs.addFormRef.validate(async valid => {
        if (!valid) return;
        this.setUserInfo();
        const {data: res} = await this.$http.post("addIn", this.addForm);
        if (res != "success") {
          return this.$message.error("入库失败~");
        }
        this.$message.success("入库成功~");
        this.addDialogVisible = false;
        this.getStockList();
      });
    },
    setUserInfo() {
      // 填入用户名
      this.addForm.worker = this.showUsername;
      this.addForm.itemname = this.selectedItems[0].name;
      this.addForm.unit = this.selectedItems[0].unit;

    },

参考GPT和自己的思路：这个报错很可能是因为你在selectedItems函数中使用了this.selectedItems而它并没有被正确声明或者赋值。所以你需要确认一下在你的代码中，是否正确声明或者赋值了this.selectedItems变量。