Steps to repro:

1. Open Unity on OSX;
2. Create new project through Launcher;
3. Observe the console.

Expected result:
No errors are thrown in the console.

Actual result:
Error:
'InvalidOperationException: Operation is not valid due to the current state of the object
System.Collections.Stack.Pop () (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.Collections/Stack.cs:329)'

is thrown after creating new project (see attached screenshot).
Regression introduced in Unity 2017.1.0a5.

Workaround is to reset Editor's layout to Default.

Notes:
- Reproducible in 2017.1.0a5 trunk, 2017.1.0a6(dev branch);
- Not reproducible in 2017.1.0a4, 5.6.0f2, 5.5.2p1;
- Reproducible only on OSX 10.12.3 (GlCore), not reproducible on Windows 10 (DX11);
- Reproducible only when creating new project through Launcher / not reproducible when upgrading project or creating new project in already opened Editor;
- This error is also shown when opening Play mode.