error on console

any idea what this means? it pops up alot on my server console

UnityEngine.DebugLogHandler:Internal_LogException_Injected(Exception, IntPtr)

UnityEngine.DebugLogHandler:Internal_LogException(Exception, Object)

UnityEngine.DebugLogHandler:LogException(Exception, Object)

UnityEngine.Logger:LogException(Exception, Object)

UnityEngine.Debug:LogException(Exception, Object)

ServerMgr:Update()

Server Exception: IndustrialStorageAdaptor.SortQueue

NullReferenceException: Object reference not set to an instance of an object

at IndustrialStorageAdaptor+NameComparer.<Compare>g__GetStringForItem|1_0 (Item i) [0x0000e] in <1e6595f6dcb64d5da96b4230eef5dd88>:0

at IndustrialStorageAdaptor+NameComparer.Compare (Item x, Item y) [0x00010] in <1e6595f6dcb64d5da96b4230eef5dd88>:0

at System.Collections.Generic.ArraySortHelper`1[T].SwapIfGreater (T[] keys, System.Comparison`1[T] comparer, System.Int32 a, System.Int32 b) [0x00004] in <41d29b352f6a475ab1bf7c6628b82790>:0

at System.Collections.Generic.ArraySortHelper`1[T].PickPivotAndPartition (T[] keys, System.Int32 lo, System.Int32 hi, System.Comparison`1[T] comparer) [0x00008] in <41d29b352f6a475ab1bf7c6628b82790>:0

at System.Collections.Generic.ArraySortHelper`1[T].IntroSort (T[] keys, System.Int32 lo, System.Int32 hi, System.Int32 depthLimit, System.Comparison`1[T] comparer) [0x00069] in <41d29b352f6a475ab1bf7c6628b82790>:0

at System.Collections.Generic.ArraySortHelper`1[T].IntrospectiveSort (T[] keys, System.Int32 left, System.Int32 length, System.Comparison`1[T] comparer) [0x00013] in <41d29b352f6a475ab1bf7c6628b82790>:0

at System.Collections.Generic.ArraySortHelper`1[T].Sort (T[] keys, System.Int32 index, System.Int32 length, System.Collections.Generic.IComparer`1[T] comparer) [0x0001c] in <41d29b352f6a475ab1bf7c6628b82790>:0

Rethrow as InvalidOperationException: Failed to compare two elements in the array.

at System.Collections.Generic.ArraySortHelper`1[T].Sort (T[] keys, System.Int32 index, System.Int32 length, System.Collections.Generic.IComparer`1[T] comparer) [0x0003c] in <41d29b352f6a475ab1bf7c6628b82790>:0

at System.Array.Sort[T] (T[] array, System.Int32 index, System.Int32 length, System.Collections.Generic.IComparer`1[T] comparer) [0x0004d] in <41d29b352f6a475ab1bf7c6628b82790>:0

at System.Collections.Generic.List`1[T].Sort (System.Int32 index, System.Int32 count, System.Collections.Generic.IComparer`1[T] comparer) [0x0002b] in <41d29b352f6a475ab1bf7c6628b82790>:0

at System.Collections.Generic.List`1[T].Sort (System.Collections.Generic.IComparer`1[T] comparer) [0x00008] in <41d29b352f6a475ab1bf7c6628b82790>:0

at IndustrialStorageAdaptor.ApplySorting () [0x00252] in <1e6595f6dcb64d5da96b4230eef5dd88>:0

at IndustrialStorageAdaptor+SortingQueue.RunJob (IndustrialStorageAdaptor entity) [0x00000] in <1e6595f6dcb64d5da96b4230eef5dd88>:0

at ObjectWorkQueue`1[T].RunQueue (System.Double maximumMilliseconds) [0x000cf] in <8e10d20e240b421abd86a54f7622c1c5>:0

at ServerMgr.Update () [0x00b4a] in <1e6595f6dcb64d5da96b4230eef5dd88>:0