Occurs error while building the project on unity: the dll is not allowed to be included or could not be found

[Greatapikachu]

ArgumentException: The Assembly UnityEditor is referenced by OpenCVForUnityCSharpDLL ('Assets/OpenCVForUnity/org/OpenCVForUnityCSharpDLL.dll'). But the dll is not allowed to be included or could not be found. UnityEditor.AssemblyHelper.AddReferencedAssembliesRecurse (System.String assemblyPath, System.Collections.Generic.List1[T] alreadyFoundAssemblies, System.String[] allAssemblyPaths, System.String[] foldersToSearch, System.Collections.Generic.Dictionary2[TKey,TValue] cache, UnityEditor.BuildTarget target) (at <4dc3f6ed6f6e4dd6a57e621ecfbb9a65>:0) UnityEditor.AssemblyHelper.AddReferencedAssembliesRecurse (System.String assemblyPath, System.Collections.Generic.List1[T] alreadyFoundAssemblies, System.String[] allAssemblyPaths, System.String[] foldersToSearch, System.Collections.Generic.Dictionary2[TKey,TValue] cache, UnityEditor.BuildTarget target) (at <4dc3f6ed6f6e4dd6a57e621ecfbb9a65>:0) UnityEditor.AssemblyHelper.FindAssembliesReferencedBy (System.String[] paths, System.String[] foldersToSearch, UnityEditor.BuildTarget target) (at <4dc3f6ed6f6e4dd6a57e621ecfbb9a65>:0) UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr, Boolean&)