I've been getting this lately and it seems to happen when new players join.
I'm guessing it's because they are in team chat from another server where they are in a team and left that server while in team chat.

Failed to call hook 'OnPlayerChat' on plugin 'BetterChat v5.2.7' (InvalidOperationException: Chat channel is set to Team, however the player is not in a team.)
  at Oxide.Plugins.BetterChat.SendBetterChatMessage (Oxide.Plugins.BetterChat+BetterChatMessage chatMessage, ConVar.Chat+ChatChannel chatchannel) [0x00158] in :0 
  at Oxide.Plugins.BetterChat.OnPlayerChat (BasePlayer bplayer, System.String message, ConVar.Chat+ChatChannel chatchannel) [0x00049] in :0 
  at Oxide.Plugins.BetterChat.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x000ed] in :0 
  at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <31122a27a2414cd799150f8677cf39d4>:0 
  at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in <0fbce81d88d64454b3e7abb24df7026b>:0 
  at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <0fbce81d88d64454b3e7abb24df7026b>:0  

Same error for me too.

Failed to call hook 'OnPlayerChat' on plugin 'BetterChat v5.2.7' (InvalidOperationException: Chat channel is set to Team, however the player is not in a team.)
at Oxide.Plugins.BetterChat.SendBetterChatMessage (Oxide.Plugins.BetterChat+BetterChatMessage chatMessage, ConVar.Chat+ChatChannel chatchannel) [0x00158] in <5f21ef9a82794e45a2f4237296236f5a>:0
at Oxide.Plugins.BetterChat.OnPlayerChat (BasePlayer bplayer, System.String message, ConVar.Chat+ChatChannel chatchannel) [0x00049] in <5f21ef9a82794e45a2f4237296236f5a>:0
at Oxide.Plugins.BetterChat.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x000ed] in <5f21ef9a82794e45a2f4237296236f5a>:0
at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <31122a27a2414cd799150f8677cf39d4>:0
at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in <0fbce81d88d64454b3e7abb24df7026b>:0
at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <0fbce81d88d64454b3e7abb24df7026b>:0

Failed to call hook 'OnPlayerChat' on plugin 'BetterChat v5.2.7' (InvalidOperationException: Chat channel is set to Team, however the player is not in a team.)

at Oxide.Plugins.BetterChat.SendBetterChatMessage (Oxide.Plugins.BetterChat+BetterChatMessage chatMessage, ConVar.Chat+ChatChannel chatchannel) [0x00158] in <b4967fa3ea2944ea96382fbbae83d40e>:0


at Oxide.Plugins.BetterChat.OnPlayerChat (BasePlayer bplayer, System.String message, ConVar.Chat+ChatChannel chatchannel) [0x00049] in <b4967fa3ea2944ea96382fbbae83d40e>:0


at Oxide.Plugins.BetterChat.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x000ed] in <b4967fa3ea2944ea96382fbbae83d40e>:0


at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <31122a27a2414cd799150f8677cf39d4>:0


at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in <0fbce81d88d64454b3e7abb24df7026b>:0


at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <0fbce81d88d64454b3e7abb24df7026b>:0

Same here

(20:35:19) | Failed to call hook 'OnPlayerChat' on plugin 'BetterChat v5.2.7' (InvalidOperationException: Chat channel is set to Team, however the player is not in a team.)

at Oxide.Plugins.BetterChat.SendBetterChatMessage (Oxide.Plugins.BetterChat+BetterChatMessage chatMessage, ConVar.Chat+ChatChannel chatchannel) [0x00158] in <39b3f3e7b0e24b3da9e53e038b10cc55>:0

at Oxide.Plugins.BetterChat.OnPlayerChat (BasePlayer bplayer, System.String message, ConVar.Chat+ChatChannel chatchannel) [0x00049] in <39b3f3e7b0e24b3da9e53e038b10cc55>:0

at Oxide.Plugins.BetterChat.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x000ed] in <39b3f3e7b0e24b3da9e53e038b10cc55>:0

at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <60c318df79ed41688ea59335e48d61ad>:0

at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in <9882f28dc2204b4dba514a9ad18f5042>:0

at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <9882f28dc2204b4dba514a9ad18f5042>:0

Failed to call hook 'OnPlayerChat' on plugin 'BetterChat v5.2.7' (InvalidOperationException: Chat channel is set to Team, however the player is not in a team.)
  at Oxide.Plugins.BetterChat.SendBetterChatMessage (Oxide.Plugins.BetterChat+BetterChatMessage chatMessage, ConVar.Chat+ChatChannel chatchannel) [0x00158] in <cac70629efec4b0d9bdef11b98e79cb4>:0

  at Oxide.Plugins.BetterChat.OnPlayerChat (BasePlayer bplayer, System.String message, ConVar.Chat+ChatChannel chatchannel) [0x00049] in <cac70629efec4b0d9bdef11b98e79cb4>:0

  at Oxide.Plugins.BetterChat.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x000ed] in <cac70629efec4b0d9bdef11b98e79cb4>:0

  at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <60c318df79ed41688ea59335e48d61ad>:0

  at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in <9882f28dc2204b4dba514a9ad18f5042>:0

  at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <9882f28dc2204b4dba514a9ad18f5042>:0

[TEAM CHAT] dongaloo[76561############] : yall lag? try having 8 gb of ram:(

Failed to call hook 'OnPlayerChat' on plugin 'BetterChat v5.2.7' (InvalidOperationException: Chat channel is set to Team, however the player is not in a team.)
  at Oxide.Plugins.BetterChat.SendBetterChatMessage (Oxide.Plugins.BetterChat+BetterChatMessage chatMessage, ConVar.Chat+ChatChannel chatchannel) [0x00158] in <0851bd5518e145dcae05d40bb0020934>:0
  at Oxide.Plugins.BetterChat.OnPlayerChat (BasePlayer bplayer, System.String message, ConVar.Chat+ChatChannel chatchannel) [0x00049] in <0851bd5518e145dcae05d40bb0020934>:0
  at Oxide.Plugins.BetterChat.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x000ed] in <0851bd5518e145dcae05d40bb0020934>:0
  at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <60c318df79ed41688ea59335e48d61ad>:0
  at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in <9882f28dc2204b4dba514a9ad18f5042>:0
  at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <9882f28dc2204b4dba514a9ad18f5042>:0

Maybe because

 Chat channel is set to Team, however the player is not in a team.)

pookins

Maybe because

 Chat channel is set to Team, however the player is not in a team.)

This player just joined my server for the first time, there is no way to create an in-game team without creating or joining a clan on my server, this player is not part of a clan and this just happened.

Steps to reproduce:

1. Join a card game.
2. Switch chat channel to Cards.
3. Leave card game.
4. Open chat and you'll continue to be in the Cards channel.
5. Send a message in the Cards channel while outside of a cards game.

Failed to call hook 'OnPlayerChat' on plugin 'BetterChat v5.2.7' (InvalidOperationException: Chat channel is set to Cards, however the player is not in a participating in a card game.)
at Oxide.Plugins.BetterChat.SendBetterChatMessage (Oxide.Plugins.BetterChat+BetterChatMessage chatMessage, ConVar.Chat+ChatChannel chatchannel) [0x00204] in <f8b8ca7667164dd0acd6c97d93b727ab>:0
at Oxide.Plugins.BetterChat.OnPlayerChat (BasePlayer bplayer, System.String message, ConVar.Chat+ChatChannel chatchannel) [0x00049] in <f8b8ca7667164dd0acd6c97d93b727ab>:0
at Oxide.Plugins.BetterChat.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x000ed] in <f8b8ca7667164dd0acd6c97d93b727ab>:0
at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <60c318df79ed41688ea59335e48d61ad>:0
at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in <12678b905a6d43c3a9cc366104306651>:0
at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <12678b905a6d43c3a9cc366104306651>:0​

Failed to call hook 'OnPlayerChat' on plugin 'BetterChat v5.2.7' (InvalidOperationException: Chat channel is set to Team, however the player is not in a team.)

at Oxide.Plugins.BetterChat.SendBetterChatMessage (Oxide.Plugins.BetterChat+BetterChatMessage chatMessage, ConVar.Chat+ChatChannel chatchannel) [0x00158] in <e7788e1fd20e4bf2b718842eb41311aa>:0

at Oxide.Plugins.BetterChat.OnPlayerChat (BasePlayer bplayer, System.String message, ConVar.Chat+ChatChannel chatchannel) [0x00049] in <e7788e1fd20e4bf2b718842eb41311aa>:0

at Oxide.Plugins.BetterChat.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x000ed] in <e7788e1fd20e4bf2b718842eb41311aa>:0

at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <60c318df79ed41688ea59335e48d61ad>:0

at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in <dfcb48ea05694263bbc08e62a39c274c>:0

at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <dfcb48ea05694263bbc08e62a39c274c>:0

(14:18:19) | Failed to call hook 'OnPlayerChat' on plugin 'BetterChat v5.2.8' (InvalidOperationException: Chat channel is set to Team, however the player is not in a team.)
  at Oxide.Plugins.BetterChat.SendBetterChatMessage (Oxide.Plugins.BetterChat+BetterChatMessage chatMessage, ConVar.Chat+ChatChannel chatchannel) [0x00158] in <27aaa0bbee224c17bee09df9a5616baf>:0 
  at Oxide.Plugins.BetterChat.OnPlayerChat (BasePlayer bplayer, System.String message, ConVar.Chat+ChatChannel chatchannel) [0x00049] in <27aaa0bbee224c17bee09df9a5616baf>:0 
  at Oxide.Plugins.BetterChat.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x000ed] in <27aaa0bbee224c17bee09df9a5616baf>:0 
  at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <60c318df79ed41688ea59335e48d61ad>:0 
  at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in <50629aa0e75d4126b345d8d9d64da28d>:0 
  at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <50629aa0e75d4126b345d8d9d64da28d>:0
(14:18:19) | [TEAM CHAT] Mishelin [76561199112XXXXXX] : .kit
(14:19:00) | Onixw has spawned
(14:19:10) | Failed to call hook 'OnPlayerChat' on plugin 'BetterChat v5.2.8' (InvalidOperationException: Chat channel is set to Team, however the player is not in a team.)
  at Oxide.Plugins.BetterChat.SendBetterChatMessage (Oxide.Plugins.BetterChat+BetterChatMessage chatMessage, ConVar.Chat+ChatChannel chatchannel) [0x00158] in <27aaa0bbee224c17bee09df9a5616baf>:0 
  at Oxide.Plugins.BetterChat.OnPlayerChat (BasePlayer bplayer, System.String message, ConVar.Chat+ChatChannel chatchannel) [0x00049] in <27aaa0bbee224c17bee09df9a5616baf>:0 
  at Oxide.Plugins.BetterChat.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x000ed] in <27aaa0bbee224c17bee09df9a5616baf>:0 
  at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <60c318df79ed41688ea59335e48d61ad>:0 
  at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in <50629aa0e75d4126b345d8d9d64da28d>:0 
  at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <50629aa0e75d4126b345d8d9d64da28d>:0
(14:19:10) | [TEAM CHAT] Mishelin [76561199112XXXXXX] : who the team?

Failed to call hook 'OnPlayerChat' on plugin 'BetterChat v5.2.8' (InvalidOperationException: Chat channel is set to Team, however the player is not in a team.)
  at Oxide.Plugins.BetterChat.SendBetterChatMessage (Oxide.Plugins.BetterChat+BetterChatMessage chatMessage, ConVar.Chat+ChatChannel chatchannel) [0x00158] in <ff41aacefd5b41a093cde7b748b5463b>:0

  at Oxide.Plugins.BetterChat.OnPlayerChat (BasePlayer bplayer, System.String message, ConVar.Chat+ChatChannel chatchannel) [0x00049] in <ff41aacefd5b41a093cde7b748b5463b>:0

  at Oxide.Plugins.BetterChat.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x000ed] in <ff41aacefd5b41a093cde7b748b5463b>:0

  at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <e23ba2c0f246426296d81c842cbda3af>:0

  at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in <50629aa0e75d4126b345d8d9d64da28d>:0

  at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <50629aa0e75d4126b345d8d9d64da28d>:0

Failed to call hook 'OnPlayerChat' on plugin 'BetterChat v5.2.10' (InvalidOperationException: Chat channel is set to Team, however the player is not in a team.)

at Oxide.Plugins.BetterChat.SendBetterChatMessage (Oxide.Plugins.BetterChat+BetterChatMessage chatMessage, ConVar.Chat+ChatChannel chatchannel) [0x00158] in <414cb9c671ba4941a020f6b617cb96ae>:0

at Oxide.Plugins.BetterChat.OnPlayerChat (BasePlayer bplayer, System.String message, ConVar.Chat+ChatChannel chatchannel) [0x00049] in <414cb9c671ba4941a020f6b617cb96ae>:0

at Oxide.Plugins.BetterChat.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x000ed] in <414cb9c671ba4941a020f6b617cb96ae>:0

at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <e23ba2c0f246426296d81c842cbda3af>:0

at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in <46ff2b534abb4b35952608167523b7ec>:0

at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <46ff2b534abb4b35952608167523b7ec>:0