[Error] Failed to call hook 'OnCardSwipe' on plugin 'PuzzlePoints v1.4.0' (InvalidOperationException: Collection was modified; enumeration operation may not execute.)
  at System.Collections.Generic.List`1+Enumerator[T].MoveNextRare () [0x00013] in <2161c9885dd04ff291b79db9349c4b9b>:0

  at System.Collections.Generic.List`1+Enumerator[T].MoveNext () [0x0004a] in <2161c9885dd04ff291b79db9349c4b9b>:0

  at Oxide.Plugins.PuzzlePoints.OnCardSwipe (CardReader cardReader, Keycard card, BasePlayer player) [0x00066] in <1870463378524550996d32979b4892d4>:0

  at Oxide.Plugins.PuzzlePoints.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x001a1] in <1870463378524550996d32979b4892d4>:0

  at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <87ce9ac9776a48658bc55eae6debe38b>:0

  at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in <18d4f19bbc844191b11ed9e69284d09b>:0

  at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <18d4f19bbc844191b11ed9e69284d09b>:0

Are you trying to modify a list while iterating through it?

Please address this.