Kubuntu 18.04 installer crashes after Disk Setup

[Dmitriy Apashanskiy]

Traceback (most recent call last):
  File "/usr/lib/ubiquity/ubiquity/frontend/kde_components/PartitionModel.py", line 66, in setData
    item.partman_column_format_toggled(value.toBool())
AttributeError: 'int' object has no attribute 'toBool'

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: ubiquity 18.04.14.12
ProcVersionSignature: Ubuntu 5.0.0-23.24~18.04.1-generic 5.0.15
Uname: Linux 5.0.0-23-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.7
Architecture: amd64
CasperVersion: 1.394
CurrentDesktop: KDE
Date: Wed Nov 6 20:09:54 2019
InstallCmdLine: BOOT_IMAGE=/casper/vmlinuz file=/cdrom/preseed/kubuntu.seed boot=casper maybe-ubiquity quiet splash ---
LiveMediaBuild: Kubuntu 18.04.3 LTS "Bionic Beaver" - Release amd64 (20190805)
SourcePackage: ubiquity
UpgradeStatus: No upgrade log present (probably fresh install)