To reproduce:
1) Open attached project
2) Open 'levelA' scene
3) Open 'levelInit' script
4) Play the scene and wait a couple of seconds for the initial flashing animations to finish
5) In 35th line, change '(i)' to '(i+1)'
6) Go back to Editor and it should crash

NOTE: Sometimes it does not crash from the first time. If so, don't stop playing the scene and just revert the save and repeat step 5. At most it took 3 tries for a crash to happen

Regression between 5.3.2p3 -> 5.3.2p4