Engine Crashes When Switching To Metal Preview While Landscape Tool Is Active

If you are in the landscape edit mode and you enable the preview shader model for High end mobile/Metal the engine will crash if you wait a while for the shaders to finish compiling.

1. Open blank project
2. Go into editor preferences and enable High end mobile/Metal preview in experimental section
3. In the viewport click on the landscape tab so that you are in landscape edit mode
4. Switch your preview level to High end mobile/Metal
5. Wait for the shaders to finish compiling

RESULT
Crash

EXPECTED
No crash and the message warning you that landscape editor doesn't work on anything lower than SM4 persists.

REGRESSION?
Yes

[Link Removed]

UE4Editor_Engine!SCWErrorCode::HandleGeneralCrash() shadercompiler.cpp:221
UE4Editor_Engine!DoReadTaskResults() shadercompiler.cpp:575
UE4Editor_Engine!FShaderCompileThreadRunnable::ReadAvailableResults() shadercompiler.cpp:1127
UE4Editor_Engine!FShaderCompileThreadRunnable::CompilingLoop() shadercompiler.cpp:1275
UE4Editor_Engine!FShaderCompileThreadRunnableBase::Run() shadercompiler.cpp:799
UE4Editor_Core!FRunnableThreadWin::Run() windowsrunnablethread.cpp:74

UE4 4.14 crashed when switching between previews