importing 'asset swap tool' (asset store originals asset) from unity asset store gives errors on build (build failed). any fixes?

I imported the tool and tried to build right away on versions 2019.1.11f1 and 2019.2.11f1 and both gave same results. Errors i get are,

• Assets\AssetStoreOriginals_SNAPS_Tools\AssetSwapTool\Scripts\SwapShader.cs(6,19): error CS0234: The type or namespace name 'PackageManager' does not exist in the namespace 'UnityEditor' (are you missing an assembly reference?)

• Assets\AssetStoreOriginals_SNAPS_Tools\AssetSwapTool\Scripts\SwapShader.cs(7,19): error CS0234: The type or namespace name 'PackageManager' does not exist in the namespace 'UnityEditor' (are you missing an assembly reference?)

• Assets\AssetStoreOriginals_SNAPS_Tools\AssetSwapTool\Scripts\SwapShader.cs(8,19): error CS0234: The type or namespace name 'Compilation' does not exist in the namespace 'UnityEditor' (are you missing an assembly reference?)

• Assets\AssetStoreOriginals_SNAPS_Tools\AssetSwapTool\Scripts\SwapTool.cs(7,19): error CS0234: The type or namespace name 'PackageManager' does not exist in the namespace 'UnityEditor' (are you missing an assembly reference?)

• Assets\AssetStoreOriginals_SNAPS_Tools\AssetSwapTool\Scripts\SwapTool.cs(8,19): error CS0234: The type or namespace name 'PackageManager' does not exist in the namespace 'UnityEditor' (are you missing an assembly reference?)

• Assets\AssetStoreOriginals_SNAPS_Tools\AssetSwapTool\Scripts\SwapTool.cs(9,19): error CS0234: The type or namespace name 'Compilation' does not exist in the namespace 'UnityEditor' (are you missing an assembly reference?)

• Assets\AssetStoreOriginals_SNAPS_Tools\AssetSwapTool\Scripts\UnpackNestedPrefab.cs(11,39): error CS0246: The type or namespace name 'EditorWindow' could not be found (are you missing a using directive or an assembly reference?)

• Assets\AssetStoreOriginals_SNAPS_Tools\AssetSwapTool\Scripts\SwapTool.cs(15,29): error CS0246: The type or namespace name 'EditorWindow' could not be found (are you missing a using directive or an assembly reference?)

• Assets\AssetStoreOriginals_SNAPS_Tools\AssetSwapTool\Scripts\SwapTool.cs(550,10): error CS0246: The type or namespace name 'MenuItemAttribute' could not be found (are you missing a using directive or an assembly reference?)

• Assets\AssetStoreOriginals_SNAPS_Tools\AssetSwapTool\Scripts\SwapTool.cs(550,10): error CS0246: The type or namespace name 'MenuItem' could not be found (are you missing a using directive or an assembly reference?)

• Error building Player because scripts had compiler errors

• Build completed with a result of 'Failed'

• UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr) UnityEditor.BuildPlayerWindow+BuildMethodException: 11 errors at UnityEditor.BuildPlayerWindow+DefaultBuildMethods.BuildPlayer (UnityEditor.BuildPlayerOptions options) [0x00242] in C:\buildslave\unity\build\Editor\Mono\BuildPlayerWindowBuildMethods.cs:194 at UnityEditor.BuildPlayerWindow.CallBuildMethods (System.Boolean askForBuildLocation, UnityEditor.BuildOptions defaultBuildOptions) [0x0007f] in C:\buildslave\unity\build\Editor\Mono\BuildPlayerWindowBuildMethods.cs:97 UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)

This is really frustrating. any fixes? :/