Steps to reproduce:
1. Create a new HDRP project or open an existing one
2. Create an empty GameObject in any Scene
3. Add a "Flare Layer" component
4. Remove the "Camera" component added together with the "Flare Layer"
5. Remove the "Flare Layer component"

Reproducible with: 2018.4.15f1, 2019.2.18f1, 2019.3.0f5, 2020.1.0a19 (HDRP 1.1.1, 4.1.0, 4.10.0, 6.9.0, 6.9.2, 7.1.7)
HDRP not available in 2017.4

First 5 lines of the stacktrace:
0x00007FF7B5C6D865 (Unity) FlareManager::Update
0x00007FF7B5C67232 (Unity) FlareManager::RenderFlares
0x00007FF7B5C8D93C (Unity) Camera::RenderLensFlares
0x00007FF7B5C843A3 (Unity) Camera::DoRenderPostLayers
0x00007FF7B50A4B99 (Unity) Camera::DoRenderGridAndPostLayers

Notes:
- Does not reproduce with the built-in renderer, "Can't remove component" error window is shown when trying to remove "Camera" component