Prerequisites:
You'll need to have collab project with some external commits that require reloading current scene.

Steps to reproduce:

1. Open Unity on OSX;
2. Open Collab project;
3. Merge latest changes and update to latest commit;
4. Reload scene and open Services tab.

Actual result:
Services tab rendering is broken. Also following errors are displayed in the console:

- 'FileNotFoundException: Could not load file or assembly 'UnityEngine.UI, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' or one of its dependencies;
- GameObject (named '_Scene Switcher') references runtime script in scene file. Fixing! - as a warning;
- ArgumentOutOfRangeException: Cannot be negative.

See attached screenshot. Editor.log file is also attached.

Expected result:
Services tab should be rendered normally with UI.

Notes:
- Happened only once on OSX 10.12;
- Didn't spot this bug on Windows 10;
- Restarting Editor fixed the problem.