Bug: SDKLauncher crashes on Linux Mint 22.2

[sour-dani]

Describe the bug

When attempting to run P2:CE SDK from either Steam or from the command line it

dani@dani-GAMING:/mnt/Videos and Games/SteamLibrary/steamapps/common/Portal 2 Community Edition/bin/linux64$ ./SDKLauncher 

(process:25788): GLib-GObject-CRITICAL **: 18:12:15.370: g_type_plugin_use: assertion 'G_IS_TYPE_PLUGIN (plugin)' failed

(process:25788): GLib-GObject-CRITICAL **: 18:12:15.370: g_type_plugin_complete_type_info: assertion 'G_IS_TYPE_PLUGIN (plugin)' failed

(process:25788): GLib-GObject-CRITICAL **: 18:12:15.370: specified class size for type 'GTlsBackend' is smaller than 'GTypeClass' size
**
GLib-GObject:ERROR:../gobject/gtype.c:2124:type_class_init_Wm: assertion failed: (node->is_classed && node->data && node->data->class.class_size && !node->data->class.class && g_atomic_int_get (&node->data->class.init_state) == UNINITIALIZED)
Bail out! GLib-GObject:ERROR:../gobject/gtype.c:2124:type_class_init_Wm: assertion failed: (node->is_classed && node->data && node->data->class.class_size && !node->data->class.class && g_atomic_int_get (&node->data->class.init_state) == UNINITIALIZED)

Launch Parameter fixes

This bug can be mitigated if:

• The user runs XDG_CURRENT_DESKTOP=kde ./SDKLauncher from the command line
• The user adds XDG_CURRENT_DESKTOP=kde %command% to their Steam launch options

@craftablescience has stated that it is likely caused by an incompatibility between the Qt version used and GTK System Themes.

To Reproduce

Context: Must be on Linux Mint 22.2 Cinnamon

1. Launch Portal 2: Community Edition SDK
   or
2. Run SDKLauncher from the Terminal

Issue Map

N/A

Expected Behavior

SDK Laucher GUI pops up.

Operating System

Linux Mint 22.2 Cinnamon