github上 下载了源代码，运行了setup.bat，之后运行GenerateProjectFiles.bat，报如下的错误：
UnrealBuildTool Exception: System.ArgumentNullException: 鍊间笉鑳戒负 null銆?
鍙傛暟鍚? path1
鍦?System.IO.Path.Combine(String path1, String path2)
鍦?UnrealBuildTool.VCProjectFileGenerator.ConfigureProjectFileGeneration(Stri
ng] Arguments, Boolean& IncludeAllPlatforms) 浣嶇疆 e:\UnrealEngine\UnrealEngin
e-4.10\Engine\Source\Programs\UnrealBuildTool\System\VCProjectFileGenerator.cs:
琛屽彿 236
鍦?UnrealBuildTool.ProjectFileGenerator.GenerateProjectFiles(String] Argumen
ts, Boolean& bSuccess) 浣嶇疆 e:\UnrealEngine\UnrealEngine-4.10\Engine\Source\Pr
ograms\UnrealBuildTool\System\ProjectFileGenerator.cs:琛屽彿 295
鍦?UnrealBuildTool.UnrealBuildTool.GenerateProjectFiles(ProjectFileGenerator
Generator, String] Arguments) 浣嶇疆 e:\UnrealEngine\UnrealEngine-4.10\Engine\S
ource\Programs\UnrealBuildTool\System\UnrealBuildTool.cs:琛屽彿 1457
鍦?UnrealBuildTool.UnrealBuildTool.DoPostStartupStuffThatCanAccessConfigs(Str
ing] Arguments) 浣嶇疆 e:\UnrealEngine\UnrealEngine-4.10\Engine\Source\Programs
\UnrealBuildTool\System\UnrealBuildTool.cs:琛屽彿 1261
请帮帮忙，谢谢！