The issue seems to be gone in 4.3 (after updating the script for new API), will consider this fixed.
Can repro in 2.81, seems fine in 4.1. ASAN build also does not complain, so i'm going to consider this fixed.
Moving this to Known Issues, since particle systems are not actively maintained.
Tagging this as a known issue, particles are not actively maintained.
I can repro in 2.81 but not 4.1 or later, will assume it's fixed and close it.
I think it should still convert the object, just make it empty. The type is still valid and can be converted, just have to avoid accessing offsets.
The crash does not happen in 4.1.1 any more (can repro in 2.81), so i'm going to assume it's fixed.
Will tag this as a known issue, particle systems are not actively maintained.
This appears to be working now (following steps from the video). Closing.