Information for an error

I was watching people use the serverrewards and I noted an error of this. 
Any idea what this could be below? Just wondering

08/08 13:27:37 | Failed to call hook 'CheckPoints' on plugin 'ServerRewards v2.0.4' (NullReferenceException: Object reference not set to an instance of an object)
at Oxide.Plugins.ServerRewards.CheckPoints (System.UInt64 userID) [0x00000] in <a0c0313cdfcd4322bb0d06cc66892cf3>:0
at Oxide.Plugins.ServerRewards.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x01354] in <a0c0313cdfcd4322bb0d06cc66892cf3>:0
at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <42f9bedc659b4f4786eb778d3cd58968>:0
at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000de] in <d59b507fd76240e5b62228d0eae39b73>:0
at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <d59b507fd76240e5b62228d0eae39b73>:0

08/08 13:27:41 | Failed to call hook 'CheckPoints' on plugin 'ServerRewards v2.0.4' (NullReferenceException: Object reference not set to an instance of an object)
at Oxide.Plugins.ServerRewards.CheckPoints (System.UInt64 userID) [0x00000] in <a0c0313cdfcd4322bb0d06cc66892cf3>:0
at Oxide.Plugins.ServerRewards.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x01354] in <a0c0313cdfcd4322bb0d06cc66892cf3>:0
at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <42f9bedc659b4f4786eb778d3cd58968>:0
at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000de] in <d59b507fd76240e5b62228d0eae39b73>:0
at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <d59b507fd76240e5b62228d0eae39b73>:0

08/08 13:27:46 | [Shop] Player Lenox (xxxxxxxx) sold item for 1 <size=14><color=#EACD32>RP</color></size>$: [ITEM-912003287] clothx8(DN: , SKIN: 0)[x1].

08/08 13:27:46 | Failed to call hook 'AddPoints' on plugin 'ServerRewards v2.0.4' (NullReferenceException: Object reference not set to an instance of an object)
at Oxide.Plugins.ServerRewards.AddPoints (System.UInt64 userID, System.Int32 amount) [0x00000] in <a0c0313cdfcd4322bb0d06cc66892cf3>:0
at Oxide.Plugins.ServerRewards.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x0290a] in <a0c0313cdfcd4322bb0d06cc66892cf3>:0
at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <42f9bedc659b4f4786eb778d3cd58968>:0
at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000de] in <d59b507fd76240e5b62228d0eae39b73>:0
at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <d59b507fd76240e5b62228d0eae39b73>:0

08/08 13:27:47 | Failed to call hook 'CheckPoints' on plugin 'ServerRewards v2.0.4' (NullReferenceException: Object reference not set to an instance of an object)
at Oxide.Plugins.ServerRewards.CheckPoints (System.UInt64 userID) [0x00000] in <a0c0313cdfcd4322bb0d06cc66892cf3>:0
at Oxide.Plugins.ServerRewards.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x01354] in <a0c0313cdfcd4322bb0d06cc66892cf3>:0
at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <42f9bedc659b4f4786eb778d3cd58968>:0
at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000de] in <d59b507fd76240e5b62228d0eae39b73>:0
at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <d59b507fd76240e5b62228d0eae39b73>:0​

check your /oxide/data/ServerRewards/player_balances.json and see if it has any data. If not, unload the plugin and delete it