MSE loop error in MSE introduction.

[Marcurius419]

When I do the tutorial "An introduction to MSE with FLR": https://flr-project.org/doc/An_introduction_to_MSE_using_FLR.html
I get an error in the final step which is the MSE loop:

set.seed(231) # set seed to ensure comparability between different runs
for(i in vy[-length(vy)]){
  # set up simulations parameters
    ay <- an(i)
    cat(i, " > ")
  flush.console()
    vy0 <- 1:(ay-y0) # data years (positions vector) - one less than current year
    sqy <- (ay-y0-nsqy+1):(ay-y0) # status quo years (positions vector) - one less than current year

  # apply observation error
    oem <- o(stk.om, idx, i, vy0)
    stk.mp <- oem$stk
    idx.mp <- oem$idx
    idx <- oem$idx.om

  # perform assessment
  out.assess <- xsa(stk.mp, idx.mp)
  stk.mp <- out.assess$stk
  
  # apply ICES MSY-like Rule to obtain Ftrgt
  # (note this is not the ICES MSY rule, but is similar)
  flag <- ssb(stk.mp)[,ac(ay-1)]<Bpa
  Ftrgt <- ifelse(flag,ssb(stk.mp)[,ac(ay-1)]*Fmsy/Bpa,Fmsy) 

  # project the perceived stock to get the TAC for ay+1
  fsq.mp <- yearMeans(fbar(stk.mp)[,sqy]) # Use status quo years defined above
  ctrl <- getCtrl(c(fsq.mp, Ftrgt), "f", c(ay, ay+1), it)
  stk.mp <- stf(stk.mp, 2)
  gmean_rec <- c(exp(yearMeans(log(rec(stk.mp)))))
  stk.mp <- fwd(stk.mp, control=ctrl, sr=list(model="mean", params = FLPar(gmean_rec,iter=it)))
  TAC[,ac(ay+1)] <- catch(stk.mp)[,ac(ay+1)]

  # apply the TAC to the operating model stock
  ctrl <- getCtrl(c(TAC[,ac(ay+1)]), "catch", ay+1, it)
  stk.om <- fwd(stk.om, control=ctrl,sr=srbh, sr.residuals = exp(srbh.res), sr.residuals.mult = TRUE)
}

The error is :

2018  > 
 Error in .local(stock, indices, ...) : 
  negative length vectors are not allowed 

It is very annoying and I don't know how to fix it. Could anyone help?