Build issue about gatsby-starter-lumen HOT 2 CLOSED

error Page data from page-data.json for the failed page "/404": {
4:39:51 PM:   "componentChunkName": "component---src-templates-not-found-template-not-found-template-tsx",
4:39:51 PM:   "path": "/404",
4:39:51 PM:   "result": {
4:39:51 PM:     "pageContext": {}
4:39:51 PM:   },
4:39:51 PM:   "staticQueryHashes": [
4:39:51 PM:     "251939775",
4:39:51 PM:     "2764776372",
4:39:51 PM:     "401334301",
4:39:51 PM:     "63107425"
4:39:51 PM:   ]
4:39:51 PM: }
4:39:51 PM: failed Building static HTML for pages - 3.712s
4:39:51 PM: error "window" is not available during Server-Side Rendering. Enable "DEV_SSR" to debug this during "gatsby develop".
4:39:51 PM: 
4:39:51 PM:   1 | const getContactHref = (name: string, contact: string) => {
4:39:51 PM:   2 |   const hrefs: { [key: string]: string } = {
4:39:51 PM: > 3 |     email: window.btoa(contact),
4:39:51 PM:     |            ^
4:39:51 PM:   4 |     line: `line://ti/p/${contact}`,
4:39:51 PM:   5 |     telegram: `https://t.me/${contact}`,
4:39:51 PM:   6 |     vkontakte: `https://vk.com/${contact}`,
4:39:51 PM: 
4:39:51 PM:   WebpackError: ReferenceError: window is not defined