Ubuntu Studio installer crashes after going back to change location. (Eraze and Reinstall Ubuntu option; multiple SSD system instalation)

[Niki Keen]

This is a bootable USB running the iso file of the latest version of Ubuntu Studio (as of 18th of December, 2018)
The installer crashed after I chose the option to Erase and Reinstall Ubuntu.
My system was running on:

/dev/sda: (500G Samsung 860 EVO Solid State Drive)
sda1: 600M UEFI partition,
sda2: 35G / ,
sda3: 464G /home ,

/dev/sdb: (500G Samsung 860 EVO Solid State Drive)
sdb1: 450G /usr
sdb2: 50G /var

ProblemType: Bug
DistroRelease: Ubuntu 18.10
Package: ubiquity 18.10.12
ProcVersionSignature: Ubuntu 4.18.0-10.11-lowlatency 4.18.12
Uname: Linux 4.18.0-10-lowlatency x86_64
ApportVersion: 2.20.10-0ubuntu13
Architecture: amd64
CasperVersion: 1.399
Date: Thu Dec 20 00:51:17 2018
InstallCmdLine: BOOT_IMAGE=/casper/vmlinuz file=/cdrom/preseed/ubuntustudio.seed boot=casper only-ubiquity quiet splash ---
LiveMediaBuild: Ubuntu-Studio 18.10 "Cosmic Cuttlefish" - Release amd64 (20181017.2)
ProcEnviron:
 LANGUAGE=en_US.UTF-8
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 LC_NUMERIC=C.UTF-8
SourcePackage: ubiquity
UpgradeStatus: No upgrade log present (probably fresh install)