Unity editor crashes when repeatedly starting and stopping the scene. The crash sometimes occurres when the editor is loading.
It seems that when the "Image" component is detached from the "Dismiss Button" Game Object, the crash does not occur (see the attached image).

To reproduce:
1. Open the "repro" project
2. Open the "test" scene
3. Play and Stop the scene numerous times

Desired outcome: The editor should play/stop the scene without crashing regardless of how many times the play/stop buttons are clicked.
Actual result: The editor crashes after about ~20 play/stop clicks.

Reproduced from 5.6.0b11, 5.6.0f1, 2017.1.0a4
Not reproduced from 5.5.3p1, 5.6.0f3, 2017.1.0a6