This assertion was randomly and rarely reproducible for a couple of years at least for me, but recently it started to happen much more often and we had a few discussions about it in ADB team, there is a PR with the fix already in flight. 

*My repro steps:*
1 Create new 3D HDRP project (or open existing one without Library folder)
2 Go to "All Materials" filter in Project Browser
3 While previews are generating - scroll in Project Browser and click on those materials which are generating previews
4 Wait a bit while more previews are generated
5 You should get those assertions in Console - if you don't - repeat from scratch

Old description:
{quote}How to reproduce:
0. Note: Reproduced using URP, reproduces only when creating and saving SG for the first time
1. Create VFX Graph
2. Create SG
3. In Graph Inspector, check Support VFX Graph' flag
4. Save SG
5. Assign it to the VFX

Actual result: Assertion failed on expression: 'i->previewArtifactID == found->second.previewArtifactID'UnityEngine.GUIUtility:ProcessEvent (int,intptr,bool&) is thrown to the console

Reproducible with: 2022.2.0a4 (14.0.1), 6000.2.0a2, 6000.1.0b2
{quote}