My 7 year old cannot play his game all of a sudden. It acts like it's going to start, but just shows us this error. I searched the thread and see it was "resolved" but couldn't find any notes on what to do? Thanks for helping. I have one sad kid here.

Game output: [08:54:18] [Client thread/INFO]: Setting user: AandCrule
[08:54:18] [Client thread/INFO]: (Session ID is token:254e1414f8a5473b9017f82dd394a7d3:cff669900ac1472988a2723a06c0a057)
Exception in thread "Client thread" java.lang.NullPointerException
at com.google.common.base.Preconditions.checkNotNull(Preconditions.java:213)
at com.google.common.collect.Lists$ReverseList.<init>(Lists.java:767)
at com.google.common.collect.Lists.reverse(Lists.java:759)
at lt.b(SourceFile:156)
at lt.<init>(SourceFile:43)
at net.minecraft.server.MinecraftServer.<init>(SourceFile:155)
at bpo.<init>(SourceFile:41)
at ave.<init>(SourceFile:293)
at net.minecraft.client.main.Main.main(SourceFile:124)
See launcher log attached too.