Switching to SM4 with LPVs active crashes Editor

Switching to SM4 when you have LPVs active in a project will crash a project.

Also reproduced in Main Promotable-CL-2589716 and 4.8.0 Launcher

[Link Removed]

1. Enable Light Propagation Volume in Console Variables.ini (r.LightPropagationVolume=1)
2. Open New Project with No Starter Content
3. In World Settings, Check True Force No Precomputed Lighting
4. Add an Unbound Post Process Volume to the level
5. In PP Volume, Leave Everything Default except check the LPV Intensity true
6. Set the Light Source to Moveable
7. Switch to Shader Model 4 by the Settings Drop Down >> Preview Rendering Level

RESULTS: Brief Pause then Crash

EXPECTED: Either a Warning that SM4 is unavailable or like Distance Fields, it reverts back to not using LPVs.