System Information
Operating system: Windows
Graphics card: Intel, RTX 3090
Blender Version
Broken: 3.3.0
Worked: N\A
There doesn't seem to be much way to add a new "Group Input" or "Group Output" node in the "Geometry Node Editor" if you delete the ones you start with.
The similat thread (https://developer.blender.org/T86276) didn't gave any correct answers and was closed. Weird.
Exact steps for others to reproduce the error
Create a geometry node tree and delete its starting nodes "Group Input" or "Group Output" from the "Geometry Node Editor".