ArgumentException: HelicopterECS.HeliStateSystem must inherit UnityEngine.Component.
What this mistake means, I can not understand
ArgumentException: HelicopterECS.HeliStateSystem must inherit UnityEngine.Component. Unity.Entities.TypeManager.BuildComponentType (System.Type type, System.Int32* writeGroups, System.Int32 writeGroupCount) (at Library/PackageCache/com.unity.entities@0.0.12-preview.24/Unity.Entities/Types/TypeManager.cs:774) Unity.Entities.TypeManager.BuildComponentType (System.Type type) (at Library/PackageCache/com.unity.entities@0.0.12-preview.24/Unity.Entities/Types/TypeManager.cs:680) Unity.Entities.TypeManager.CreateTypeIndexThreadSafe (System.Type type) (at Library/PackageCache/com.unity.entities@0.0.12-preview.24/Unity.Entities/Types/TypeManager.cs:643) Unity.Entities.TypeManager.GetTypeIndex (System.Type type) (at Library/PackageCache/com.unity.entities@0.0.12-preview.24/Unity.Entities/Types/TypeManager.cs:502) Unity.Entities.ComponentType..ctor (System.Type type, Unity.Entities.ComponentType+AccessMode accessModeType) (at Library/PackageCache/com.unity.entities@0.0.12-preview.24/Unity.Entities/Types/ComponentType.cs:93) Unity.Entities.ComponentType.op_Implicit (System.Type type) (at Library/PackageCache/com.unity.entities@0.0.12-preview.24/Unity.Entities/Types/ComponentType.cs:118) HelicopterECS.Bootstrap.Start () (at Assets/Script/Temp/bin/Release/Bootstrap.cs:22)