Crash when using /clone on complex structure(command block and pulser)

Almost every time, when I try to move this structure by one block in any direction (by cloning a sifted base structure on the old one), the game crash (no data corruption), The problem probably come from the combo : pulser, command block and comparator, because when I turn the pulser off there is no more crash (maybe one).

Description: Unexpected error

java.lang.ClassCastException: arg cannot be cast to are
	at alx.a(SourceFile:62)
	at bof.a(SourceFile:279)
	at bdh.ai(SourceFile:1233)
	at bdh.p(SourceFile:1569)
	at bdh.ag(SourceFile:778)
	at bdh.f(SourceFile:732)
	at net.minecraft.client.main.Main.main(SourceFile:154