Debug a Empty Game on iOS device crash at startup

lerror: [File:/Users/build/Build/++UE4/Sync/Engine/Source/Runtime/CoreUObject/Private/Serialization/AsyncLoading.cpp] [Line: 6963]
LoadPackageAsync failed to begin to load a package because the supplied package name was neither a valid long package name nor a filename of a map within a content folder: ‘’
2018-12-15 22:16:27.527392 IosRunDebug[709:236703] [2018.12.15-14.16.27:527][ 0]LogGenericPlatformMisc: FPlatformMisc::RequestExit(1)
(lldb)

UE4:4.21
xcode version:10.1
Mac os:10.13.6