comment out site icon for now (so build doesn't fail)

frontend/gatsby-config.js

@@ -44,7 +44,7 @@ module.exports = {
         background_color: `#663399`,
         theme_color: `#663399`,
         display: `minimal-ui`,
-        icon: ``, // This path is relative to the root of the site.
+        //icon: ``, // This path is relative to the root of the site.
       },
     },
     // this (optional) plugin enables Progressive Web App + Offline functionality