replacement has length zero in list() in r - r

Question

I'm trying to run this code, and I'm using mhadaptive package, but the problem is that when I run these code without writing metropolis_hastings (that is one part of mhadaptive package) error does not occur, but when I add mhadaptive package the error occur. What should I do?
li_F1<-function(pars,data) #defining first function
{
a01<-pars[1] #defining parameters
a11<-pars[2]
epsilon<<-pars[3]
b11<-pars[4]
a02<-pars[5]
a12<-pars[6]
b12<-pars[7]
h<-pars[8]
h[[i]]<-list() #I want my output is be listed in the h
h[[1]]<-0.32082184 #My first value of h is known and other values should calculate by formula
for(i in 2:nrow(F_2_))
{
h[[i]]<- ((a01+a11*(h[[i-1]])*(epsilon^2)*(h[[i-1]])*b11)+(F1[,2])*((a02+a12*(h[[i-1]])*(epsilon^2)+(h[[i-1]])*b12)))
pred<- h[[i]]
}
log_likelihood<-sum(dnorm(prod(h[i]),pred,sd = 1 ,log = TRUE))
return(h[i])
prior<- prior_reg(pars)
return(log_likelihood + prior)
options(digits = 22)
}
prior_reg<-function(pars) #defining another function
{
epsilon<<-pars[3] #error
prior_epsilon<-pt(0.95,5,lower.tail = TRUE,log.p = FALSE)
return(prior_epsilon)
}
F1<-as.matrix(F_2_) #defining my importing data and simulatunig data with them
x<-F1[,1]
y<-F1[,2]
d<-cbind(x,y)
#using mhadaptive package
mcmc_r<-Metro_Hastings(li_func = li_F1,pars=c(10,15,10,10,10,15),par_names=c('a01','a02','a11','a12','b11','b12'),data=d)
By running this code this error occur.
Error in h[[i]] <- list() : replacement has length zero
I'll so much appreciate who help me.