解决echarts地图geoJson报错问题（“echarts.min.js:45 Uncaught Error: Invalid geoJson format Cannot read prope”）

背景

解决报错：
1.Invalid geoJson format Cannot read property 'length' of undefined
2 echarts.min.js:45 Uncaught Error: Invalid geoJson format Cannot read prope
项目中用echarts绘制地图，由于网上乡镇级别行政边界地图贼少，所以需要用到bigMap+geojson.io去绘制自定义地图，详情请看解决如何整理出乡镇级的地图json，以此使用echarts绘制出乡镇级的数据
但是由于生成的地图里有一个区域为两块不连续的地图块，所以生成的geoJson中此区域的geometry.type===GeometryCollection.
然而 echarts 中对于此类型没有做处理，详情见源码
echarts\lib\coord\geo\parseGeoJson.js
第133行左右

这段代码的意思是解析geoJson

解决方法

需要修改如下函数：
echarts 源代码 大约121行

function _default(geoJson, nameProperty) {}

直接复制粘贴：

function _default(geoJson, nameProperty) {
    decode(geoJson);
    return zrUtil.map(
        zrUtil.filter(geoJson.features, function(featureObj) {
            if (featureObj.geometry.geometries) {
                let geometry = featureObj.geometry.geometries.map(i => {
                    return i.coordinates;
                });
                let { type, properties, ...params } = featureObj;
                return { type, properties, geometry };
            }
            // Output of mapshaper may have geometry null
            return (
                featureObj.geometry &&
                featureObj.properties &&
                featureObj.geometry.coordinates &&
                featureObj.geometry.coordinates.length > 0
            );
        }),
        function(featureObj) {
            var properties = featureObj.properties;
            var geo = featureObj.geometry;
            var coordinates = geo.coordinates;
            var geometries = [];
            if (geo.type === "GeometryCollection") {
                let geometry = {
                    type: "Polygon"
                };
                let coordinatesArr = featureObj.geometry.geometries.map(i => {
                    return i.coordinates;
                });
                geometry.coordinates = coordinatesArr;
                console.log(coordinatesArr, "coordinatesArr");
                coordinatesArr.forEach(i => {
                    geometries.push({
                        type: "polygon",
                        // According to the GeoJSON specification.
                        // First must be exterior, and the rest are all interior(holes).
                        exterior: i[0],
                        interiors: i.slice(1)
                    });
                });
            }
            if (geo.type === "Polygon") {
                console.log("coordinatesPolygon", coordinates);
                geometries.push({
                    type: "polygon",
                    // According to the GeoJSON specification.
                    // First must be exterior, and the rest are all interior(holes).
                    exterior: coordinates[0],
                    interiors: coordinates.slice(1)
                });
            }
            if (geo.type === "MultiPolygon") {
                zrUtil.each(coordinates, function(item) {
                    if (item[0]) {
                        geometries.push({
                            type: "polygon",
                            exterior: item[0],
                            interiors: item.slice(1)
                        });
                    }
                });
            }
            console.log(
                properties[nameProperty || "name"],
                geometries,
                properties.cp,
                "asdfasdfasdf"
            );
            var region = new Region(
                properties[nameProperty || "name"],
                geometries,
                properties.cp
            );
            region.properties = properties;
            return region;
        }
    );
}

ps: 去git上看echarts之前的issues，有类似问题，修改前可以去该issues参观一下