Posit.cloud: tutorials are becoming grey

**Fehler:**
`pandoc document conversion failed with error 1`
`Warning: an error occurred while inside render_exercise() for exercise 'filter'`
`[1] Delaying exercise execution due to forked proc limits`


**Zum Replizieren**
Schritte, um den Fehler zu erzeugen:
1. Tutorial-Name `1a_intro`


**Erwartetes Verhalten**
Kein Einfrieren des Tutorials

**Betriebssytem**

- RStudio Cloud (suspected Linux)
