When trying to dock an Inspector window in the Editor, OnGUIDepth errors spam the console.

1. Create a new project
2. Try to dock/undock the Inspector window

Actual Result:
OnGUIDepth Errors spam the console when docking the Inspector window

Expected Result:
Inspector window docked gracefully

Reproducible in:
2021.1.0a10, 2021.1.0a2, 2020.2.0f1, 2020.2.0b10

Working Fine in:
2021.1.0a1, 2020.2.0b9

Environment: Occurs only on Linux

Tested on Ubuntu 18.04 LTS