Steam crashes when failing to fetch CD-keys for the ingame overlay

[cverstege]

Your system information

• Steam client version (build number or date): Oct 28 2020 at 23:35:02 / 1603992987
• Distribution (e.g. Ubuntu): Manjaro
• Opted into Steam client beta?: No
• Have you checked for system updates?: Yes

Please describe your issue in as much detail as possible:

When launching Assassin's Creed 2 (33230) via Proton, Steam crashes as soon as the game starts in fullscreen and the steam overlay appears (after uplay finishes initializing). The game itself keeps running just fine and is perfectly playable. I think this is because Steam tries to fetch the CD Keys an fails doing so.

In order to get AC2 running with Proton some tinkering is necessary, as described in the steps below. (See ValveSoftware/Proton#190 (comment))
This is due to issues with a Mac only DLC and different keys for the game on windows and mac. This is handled via the DLCs and Steam installs all DLCs in Linux.

Steps for reproducing this issue:

1. Install Assassin's Creed 2
2. Symlink $WINEPREFIX/drive_c/Program Files (x86)/Steam/appcache/appinfo.vdf to $HOME/.local/share/Steam/appcache/appinfo.vdf
3. Run SteamEdit via wine and hide the Mac DLC (https://steamdb.info/app/33362/). This is necessary for the game to even launch. Otherwise it will already shows an error, that requesting the keys failed. See Assassin's Creed II (33230) Proton#190 (comment)
4. Maybe install the Crypt32 DLL via protontricks for Uplay to be able to install updates (otherwise stuck at "looking for patches" see https://www.reddit.com/r/Lutris/comments/g6y4fe/fix_uplays_looking_for_patches_loop/) or install a never version of uplay with protontricks
5. Launch the game
6. Steam crashes as soon as it's loading the in game overlay.

Crash IDs:
CrashID=bp-edb01180-9442-4042-a5dc-7e19e2201128
CrashID=bp-93e1e572-e9fa-4042-9b54-46e2e2201128
CrashID=bp-67177472-2700-4ba4-8a1a-b819c2201128
Those should all have the same reason

Workaround:
Disable Steam Overlay for this Game. Steam keeps running and counting your playtime.

Edit: Add link to SteamEdit
Edit2: Add symlink before running SteamEdit through wine

[cverstege]

Most probably related to #212 and #5649

[cverstege]

This does also happen for Assassin's Creed Brotherhood (48190). The same tricks (hide mac dlc) are needed to launch the game, when in game and the steam overlay should be loaded, steam crashes.
A crash dump was uploaded:
CrashID=bp-e1e39abb-fc8a-41c5-876f-21db02210920

Disabling the steam overlay, keeps the steam client running.