[Linux] Download assistant crashes starting on ComponentManager::Initialize()

As of the latest trunk (2019.3.a12), running the download assistant/UnitySetup with specifying the INI file, will produce an error and crash:

Error loading settings, aborting
==18613== Invalid read of size 8
==18613== at 0x120F87: ComponentManager::Initialize() (in /home/teddy.kardos/Downloads/UnitySetup)
==18613== by 0x125A3A: OnMainWindowShown (in /home/teddy.kardos/Downloads/UnitySetup)
==18613== by 0x4F7CBDB: ??? (in /usr/lib64/libgtk-x11-2.0.so.0.2400.31)
==18613== by 0x710F987: g_closure_invoke (in /usr/lib64/libgobject-2.0.so.0.5600.1)
==18613== by 0x712205C: ??? (in /usr/lib64/libgobject-2.0.so.0.5600.1)
==18613== by 0x7129CDB: g_signal_emit_valist (in /usr/lib64/libgobject-2.0.so.0.5600.1)
==18613== by 0x712A2DE: g_signal_emit (in /usr/lib64/libgobject-2.0.so.0.5600.1)
==18613== by 0x50ACDC3: ??? (in /usr/lib64/libgtk-x11-2.0.so.0.2400.31)
==18613== by 0x4F7B39A: gtk_main_do_event (in /usr/lib64/libgtk-x11-2.0.so.0.2400.31)
==18613== by 0x5518A0B: ??? (in /usr/lib64/libgdk-x11-2.0.so.0.2400.31)
==18613== by 0x739C048: g_main_context_dispatch (in /usr/lib64/libglib-2.0.so.0.5600.1)
==18613== by 0x739C3A7: ??? (in /usr/lib64/libglib-2.0.so.0.5600.1)
==18613== Address 0x0 is not stack'd, malloc'd or (recently) free'd

Steps to reproduce-
- On a machine running CentOS 7, obtain the installer for Unity 2019.3.0a12 (or greater)
- In a terminal, change directory to where the installer is located
- Run the installer with the following command: ./UnitySetup -v --inifile=unity-2019.3.0a12-linux.ini
- Observe the installer will crash on start up