Creating partition with larger size crashes installer

[Joshua Powers]

Summary:
When attempting to add a partition with size larger than available crashes and restarts.

Expected Result:
I can add a partition or get told that is too large. No crashing

Actual Result:
Installer crashes

Steps to Reproduce:
1. Download live ISO from 2018-07-11 md5sum: 9e2a51144591db71afd21e6c50d8182f
2. qemu-img create -f raw target.img 10G
3. qemu-img create -f raw target2.img 10G
4. kvm -m 1024 -boot d -cdrom bionic-live-server-amd64.iso -hda target.img -hdb target2.img -serial stdio
5. Accept all defaults once you get to the disk selection select either "Use An Entire Disk" or "Use an Entire Disk And Set Up LVM" either option will cause this issue
6. Before clicking "Done" on Filesystem setup, scroll up to the 2nd HD under Available devices.
7. Click the 2nd HD, choose add partition, and enter a size larger than what is available (e.g. if 9.96GB is available, type 10)
8. Crash

[Michael Hudson-Doyle (mwhudson)]

Fixed in git, thanks for the report!