1) Add a networked object in your scene (in my case, a VRCObjectSynced object that had a station as child GameObject)

2) Click on "play"

-> Play mode works

3) Now, delete that object

4) Click on "play" again

-> Play mode crashes with an error (see screenshot)

To fix that issue, I need to regenerate network IDs, so it's probably a network ID related issue.