Comment 9 for bug 1875903

@electr0

This bug is fixed, your crash file, we can see sfdisk --json being used:

Verifying /dev/sda2 exists
 Running command ['sfdisk', '--json', '/dev/sda'] with allowed return codes [0] (capture=True)
 Verifying /dev/sda2 size, expecting 86564143104 bytes, found 86564143104 bytes
 Device /dev/sda2 ptable entry: {
  "node": "/dev/sda2",
  "size": 169070592,
  "start": 61442048,
  "type": "83"
 }
 Verifying /dev/sda2 partition flag, expecting linux, found None
 An error occured handling 'partition-sda2': RuntimeError - Verifying /dev/sda2 partition flag, expecting linux, found None

This path is a new, we'll fix this in https://bugs.launchpad.net/ubuntu/+source/curtin/+bug/1878890