I tested on my server got this error
12/14/2023 - 09:42:19: SourceMod error session started
L 12/14/2023 - 09:42:19: Info (map "mercy_xmas1") (file "C:\servers\kruffty2\left4dead2\addons\source mod\logs\errors_20231214.log")
L 12/14/2023 - 09:42:19: [SM] Exception reported: Client index 0 is invalid
L 12/14/2023 - 09:42:19: [SM] Blaming: autoServerSlot.smx
L 12/14/2023 - 09:42:19: [SM] Call stack trace:
L 12/14/2023 - 09:42:19: [SM] [0] IsFakeClient
L 12/14/2023 - 09:42:19: [SM] [1] Line 209, autoServerSlot.sp::OnPlayerDisconnect
L 12/14/2023 - 09:42:19: [SM] Exception reported: Client index 0 is invalid
L 12/14/2023 - 09:42:19: [SM] Blaming: autoServerSlot.smx
L 12/14/2023 - 09:42:19: [SM] Call stack trace:
L 12/14/2023 - 09:42:19: [SM] [0] IsFakeClient
L 12/14/2023 - 09:42:19: [SM] [1] Line 209, autoServerSlot.sp::OnPlayerDisconnect
L 12/14/2023 - 09:42:19: [SM] Exception reported: Client index 0 is invalid
L 12/14/2023 - 09:42:19: [SM] Blaming: autoServerSlot.smx
L 12/14/2023 - 09:42:19: [SM] Call stack trace:
L 12/14/2023 - 09:42:19: [SM] [0] IsFakeClient
L 12/14/2023 - 09:42:19: [SM] [1] Line 209, autoServerSlot.sp::OnPlayerDisconnect
L 12/14/2023 - 09:42:19: [SM] Exception reported: Client index 0 is invalid
L 12/14/2023 - 09:42:19: [SM] Blaming: autoServerSlot.smx
L 12/14/2023 - 09:42:19: [SM] Call stack trace:
L 12/14/2023 - 09:42:19: [SM] [0] IsFakeClient
L 12/14/2023 - 09:42:19: [SM] [1] Line 209, autoServerSlot.sp::OnPlayerDisconnect
L 12/14/2023 - 09:42:19: [SM] Exception reported: Client index 0 is invalid
L 12/14/2023 - 09:42:19: [SM] Blaming: autoServerSlot.smx
L 12/14/2023 - 09:42:19: [SM] Call stack trace:
L 12/14/2023 - 09:42:19: [SM] [0] IsFakeClient
L 12/14/2023 - 09:42:19: [SM] [1] Line 209, autoServerSlot.sp::OnPlayerDisconnect
L 12/14/2023 - 09:42:22: [SM] Exception reported: Client index 0 is invalid
L 12/14/2023 - 09:42:22: [SM] Blaming: autoServerSlot.smx
L 12/14/2023 - 09:42:22: [SM] Call stack trace:
L 12/14/2023 - 09:42:22: [SM] [0] IsFakeClient
L 12/14/2023 - 09:42:22: [SM] [1] Line 209, autoServerSlot.sp::OnPlayerDisconnect
L 12/14/2023 - 09:42
1: Error log file session closed.