Steps to repro:

1. Open Unity Launcher on OSX;
2. Click 'New';
3. Click 'Add Asset Package';
4. Select any asset package (e.g. 2D) and click Done;
5. Click 'Create project'.

Expected result:
Project is opened and packages are imported.

Actual result:
Editor crashes. See attached video.

Regression introduced in Unity 5.6.0b5.

Notes:
- Reproducible in 5.6.0b5; not reproducible in 5.6.0b4;
- Reproducible only on OSX (10.12.2 checked), not reproducible on Windows 10;
- Not reproducible when creating project without asset packages added.