Installer no longer works as updater

[jonasw234]

Bug Report

The Windows installer no longer works as updater.
Previously it was possible to use gpt4all-installer-win64-v3.4.2.exe --accept-licenses --default-answer --confirm-command update to update an existing installation. However, since v3.5.0 this feature broke.

gpt4all-installer-win64-v3.5.3.exe --accept-licenses --default-answer --confirm-command update
[0] Arguments: gpt4all-installer-win64-v3.5.3.exe, --accept-licenses, --default-answer, --confirm-command, update
[5] Operations sanity check succeeded.
[12] Using metadata cache from "C:/Users/Administrator/AppData/Local/cache\\qt-installer-framework\\9c11e018-d3aa-3c3a-9118-829c9ab85b1c"
[13] Found 0 cached items.
[17] Loaded control script ":/metadata/installer-config/installer_control_qs.qs"
[17] Warning: Cannot update packages with installer.

Since I’m the maintainer for https://community.chocolatey.org/packages/gpt4all (also requested in #1709), I would like to have a standardized way of upgrading the installation instead of having to go the manual route and uninstall first before updating the package.

Steps to Reproduce

1. Install an old version of GPT4All
2. Download the latest installer from the releases (gpt4all-installer-win64-v3.5.3.exe)
3. Run the installer from the command line with the parameters --accept-licenses --default-answer --confirm-command update

Expected Behavior

The installer upgrades an existing installation.

Your Environment

• GPT4All version: 3.5.3
• Operating System: Windows 10