update download fn

src/js/07-header.js

@@ -17,12 +17,14 @@
     var pathname = window.location.pathname
     var path = pathname.split('/')
     var filename = path[2] ? path[2] === 'swlab-docs' ? 'docs' : `docs-${path[2]}` : ''
-    var directory = path[2] && path[3] ? path[2] === 'swlab-docs' ? 'docs' : path[3] : ''
+    var directory = path[2] && path[3] ? path[2] === 'swlab-docs' ? path[2] : path[3] : ''
     var link = document.createElement('a')
 
     link.href = `http://182.162.100.110:10001/download-file?filename=${filename}.zip&directory=${directory}`
     link.click()
 
-    document.removeChild(link)
+    if (link.parentNode) {
+      document.body.removeChild(link)
+    }
   })
 })()