Error: Invalid Frontmatter

Path: /var/www/grav-admin/user/pages/resources/default.en.md

Failed to read /var/www/grav-admin/user/pages/resources/default.en.md: Malformed inline YAML string: 'noindex,nofollow at line 7 (near "robots: 'noindex,nofollow").

---
slug: materialy
routable: true
visible: false
sitemap:
    ignore: true
meta:
    robots: 'noindex,nofollow
---