[MC-30903] scoreboard @r NullPointerException when server empty

put a timer attached to command blocks with these commands in order:

/scoreboard objectives remove ActivePlayer
/scoreboard objectives add ActivePlayer dummy
/scoreboard players set @r ActivePlayer 1

Once the server goes empty, when the third command gets issued, the following NPE is displayed in the console:

java.lang.NullPointerException
>       at java.util.Collections.shuffle(Collections.java:497)
>       at java.util.Collections.shuffle(Collections.java:469)
>       at ac.c(SourceFile:126)
>       at ac.a(SourceFile:43)
>       at x.e(SourceFile:124)
>       at iv.l(SourceFile:501)
>       at iv.b(SourceFile:91)
>       at y.a(SourceFile:55)
>       at aud.a(SourceFile:45)
>       at apo.a(SourceFile:48)
>       at kd.a(SourceFile:404)
>       at kd.b(SourceFile:131)
>       at net.minecraft.server.MinecraftServer.t(SourceFile:455)
>       at jd.t(SourceFile:262)
>       at net.minecraft.server.MinecraftServer.s(SourceFile:398)
>       at net.minecraft.server.MinecraftServer.run(SourceFile:332)
>       at hr.run(SourceFile:575)