unicloud-db中写的where条件，在h5中正常，运行到微信小程序编译报错

代码片段：

<unicloud-db v-slot:default="{data, loading, error, options}" collection="talk-group">  
            <view v-if="error">{{error.message}}</view>  
            <view v-else>  
                <block v-for="item in data" :key="item._id">  
                    <uni-section :title="item.name" style="margin: 0;" type="line"></uni-section>  
                    <unicloud-db v-slot:default="{data, loading, error, options}" :where="`group == '${item._id}'`"  
                        collection="talk">  
                        <view v-if="error">{{error.message}}</view>  
                        <view v-else-if="data.length>0" class="tag-container">  
                            <my-tag v-for="tag in data" :key="tag._id" :text="tag.name"  
                                @click="showTalkDetail(tag._id)" />  
                        </view>  
                        <view v-else>  
                            <text class="empty">暂无数据</text>  
                        </view>  
                    </unicloud-db>  
                </block>  
            </view>  
        </unicloud-db>

小程序报错页面