Light min roughness set to 0 will create black artifacts on materials with negative roughness value

Any light's min roughness setting creates black artifacts with materials who have a roughness value less than 0. The min roughness must be =< 0.

1. Open Blank Project
2. Drag a basic sphere into the scene
3. Open the material and set the roughness to any negative value.
4. Open the directional light and set it to movable
5. Set the min roughness value to 0

RESULT
The sphere will display a large black area.

EXPECTED
The sphere looks mostly similar aside from the glossy highlight.