Exception thrown in one of the use-cases

[Lookout-ent]

I'm using acorn for parsing
Input : function testing(){
var la = qr && 1 / br(new qr([, -0]))[1] == w
/okay/
return true;
}

while attaching comments using astravel, i see some exceptions
I believe code is missing some null check 
if u see **[, -0]** , first element is null which is causing problem in astravel 

let me know if u are planning to fix this