The Assembly UnityEditor is referenced by Assembly-CSharp-firstpass ('Library/ScriptAssemblies/Assembly-CSharp-firstpass.dll'). But the dll is not allowed to be included or could not be found.

I'm getting an error when I'm building using batch mode only and not when compiling using the Editor. Running Build -> Steam Full from the editor works just fine and compiles ok, but running in batch mode does not.

The odd issue about this error is that Assembly-CSharp-firstpass.dll is supposed to reference UnityEngine and the fact it's complaining about it seems like a bug. I used ILSpy to examine the binary from the build in editor that succeeds and it's referencing UnityEditor as expected.

Exception in Log File

 ArgumentException: The Assembly UnityEditor is referenced by Assembly-CSharp-firstpass ('Library/ScriptAssemblies/Assembly-CSharp-firstpass.dll'). But the dll is not allowed to be included or could not be found.
   at UnityEditor.AssemblyHelper.AddReferencedAssembliesRecurse (System.String assemblyPath, System.Collections.Generic.List`1[T] alreadyFoundAssemblies, System.String[] allAssemblyPaths, System.String[] foldersToSearch, System.Collections.Generic.Dictionary`2[TKey,TValue] cache, UnityEditor.BuildTarget target) [0x00255] in C:\buildslave\unity\build\Editor\Mono\AssemblyHelper.cs:155 
   at UnityEditor.AssemblyHelper.FindAssembliesReferencedBy (System.String[] paths, System.String[] foldersToSearch, UnityEditor.BuildTarget target) [0x0001e] in C:\buildslave\unity\build\Editor\Mono\AssemblyHelper.cs:195 
 UnityEditor.BuildPipeline:BuildPlayerInternalNoCheck(String[], String, String, BuildTargetGroup, BuildTarget, BuildOptions, Boolean)
 UnityEditor.BuildPipeline:BuildPlayerInternal(String[], String, String, BuildTargetGroup, BuildTarget, BuildOptions) (at C:\buildslave\unity\build\Editor\Mono\BuildPipeline.bindings.cs:359)
 UnityEditor.BuildPipeline:BuildPlayer(String[], String, String, BuildTargetGroup, BuildTarget, BuildOptions) (at C:\buildslave\unity\build\Editor\Mono\BuildPipeline.bindings.cs:254)
 UnityEditor.BuildPipeline:BuildPlayer(BuildPlayerOptions) (at C:\buildslave\unity\build\Editor\Mono\BuildPipeline.bindings.cs:237)
 UnityEditor.BuildPipeline:BuildPlayer(EditorBuildSettingsScene[], String, BuildTarget, BuildOptions) (at C:\buildslave\unity\build\Editor\Mono\BuildPipeline.bindings.cs:220)
 Build:BuildSteamFull() (at Assets\Editor\Scripts\Build\Build.cs:113)

Command to Build Project

 "C:\Program Files\Unity-2018.2.6f1\Editor\Unity.exe" -quit -batchMode -executeMethod Build.BuildSteamFull -logFile ..\Bin\build.log -nographics -outputDir "..\Bin"

The Function To Build The Client

 [MenuItem("Build/Steam Full")]
     public static bool BuildSteamFull()
     {
         string outputFile = GetOutputFile(BuildPlatform.Steam);
         EditorBuildSettingsScene[] scenes = GetFullPlaylist();
         PlayerSettings.SetScriptingDefineSymbolsForGroup(BuildTargetGroup.Standalone, "STEAM;STEAMWORKS_WIN;UNITY;__MEGASPLAT__;VEGETATION_STUDIO;CTS_PRESENT;UNITY_POST_PROCESSING_STACK_V2");
         BuildReport report = BuildPipeline.BuildPlayer(scenes, outputFile, BuildTarget.StandaloneWindows64, BuildOptions.None);
         if (!Build.DidBuildFail(report))
         {
             return false;
         }
         CopyStaticFolderToOutput(Path.GetDirectoryName(outputFile));
         return true;
     }