bug fix

src/pages/building/list/add/components/imageSet.jsx

       title: '套内面积',
       dataIndex: 'insideArea',
       key: 'insideArea',
-      render: (insideArea, _) => <span>{ `${insideArea}m²` }</span>,
+      render: (insideArea, _) => <span>{ `${insideArea === null ? "-" : insideArea + "m²"}` }</span>,
     },
     {
       title: '创建时间',