地图getRegion第二次打开报错

第一次打开页面没问题，退出再进，就会报错。
是这个操作流程吧，请确认下。

首页->有地图的页面->调用API->返回->再次打开有地图的页面->调用API。
按照这个步骤操作，没有重现问题，始终走的 success。

<template>  
    <view class="map">  
        <map id="map" :latitude="latitude" :longitude="longitude" :markers="covers">  
        </map>  
    </view>  
</template>  
<script>  
    export default {  
        data() {  
            return {  
                title: 'map',  
                latitude: 28.204039,  
                longitude: 112.985415,  
                covers: []  
            }  
        },  
        onLoad() {  

            var map = uni.createMapContext('map');  
            map.getRegion({  
                success: function(res) {  
                    console.log(JSON.stringify(res));  
                },  
                fail: (data, code) => {  
                    console.log('fail' + JSON.stringify(data));  
                }  
            });  
        },  
        methods: {  
            //点击标记  
            makertap: function(e) {  
                console.log("1");  
            },  
            //点击气泡  
            callouttap: function(e) {  
                console.log("2");  
            },  
            //地图视野发生变化  
            regionchange: function(e) {  
                console.log("3");  
            }  
        },  
        components: {  

        }  
    }  
</script>  
<style>  
    .map {  
        width: 100%;  
        position: fixed;  
        top: 0;  
        bottom: 0;  
        text-align: center;  
        background: #FFFFFF;  
    }  

    map {  
        width: 100%;  
        height: 100%;  
    }  
</style>

操作流程没错，我把代码放上来
错误代码是
11:56:52.773 [ERROR] : thirdScriptError
11:56:52.773 null is not an object (evaluating 'bounds.northease');at pages/list/map onShow function;at setTimeout callback function
11:56:52.773 getBounds@uniappservice.html:4199:34
11:56:52.773 f8@uniappservice.html:1:46232
11:56:52.773 N2@uniappservice.html:1:84364
11:56:52.773 m1L@uniappservice.html:1:86426
11:56:52.773 s1L@uniappservice.html:1:86906
11:56:52.773 q5b@uniappservice.html:1:220409
11:56:52.773 W7o@uniappservice.html:1:221750
11:56:52.773 value@uniappservice.html:1:358215
11:56:52.773 uniappservice.html:1:358529
11:56:52.773 uniappservice.html:1:249941
11:56:52.773 uniappservice.html:1:356458
11:56:52.773 uniappservice.html:1:220951
11:56:52.774 g1L@uniappservice.html:1:87391
11:56:52.774 C4@uniappservice.html:1:84217
11:56:52.774 uniappservice.html:1:273
11:56:52.774 uniappservice.html:1:193351
11:56:52.774 __uniappservice.html:1:398729