Reproduction Steps:
1. Open Project
2. Open "ImageFlip.cs"
3. Make sure that variable at line 11 is set to public
like this: public Material _material;
4. Open Game view (do not start)
5. Click a few times on the screen if needed
6. Crash should occur
--
7. If it does not crash make variable not public, like this "Material _material;"
8. Do 4 and 5 steps again
9. Crash should occur

Expected behaviour: Error is thrown as script and shader are unfinished.
Actual result: When accessibility of variable _material is changed, crash occurs.

Reproduced on versions: Unity 5.5.0b11, 5.5.0p4, 5.6.0b3
Did not reproduce on versions: Unity 5.4.4p1, 5.5.0b10
Regression introduced: Unity 5.5.0b11