Title of this page: http://www.conversaschool.nl/mission/

[pandusia]

is Conversa School | undefined.

Please change it to Conversa School | Mission

[mdvanes]

Good find. Please be advised this is visible to the entire world, because your screenshot contained private information.

Solution probably: https://github.com/gatsbyjs/gatsby-starter-kitchen-sink/blob/master/pages/html.html