Reproduction steps:
1. Create or open any Unity project
2. Set the Layout to "Default"
3. Create a new GameObject in the Hierarchy4
4. Add Coillder component (Sphere, Box, Capsule)
5. Edit collider bounds
6. While still in the bound edit mode, remove the collider component through the Inspector

Expected: No errors are thrown
Actual: 'MissingReferenceException' and GUI errors are thrown

Reproducible with: 2019.3.15f1, 2019.4.2f1, 2020.1.0b14, 2020.2.0a16
Not reproducible with: 2018.4.23f1, 2019.3.14f1

Notes:
1. Errors can be cleared from the console and do not seem to affect the project in any way
2. Reproduced with collider components: Box, Sphere, Capsule
3. Does not reproduce with collider components: Box2D, Circle2D, Capsule2D, Edge2D, Polygon2D
4. The issue only reproduces when using the Default Layout.