FlowSOM randomly stops because of missing consensus.pdf

I am using FlowSOM() Clustering from the FlowSOM and am getting an error while a vectorized function is running:

Error in map2(): ℹ In index: 8. ℹ With name: FileID8. Caused by error in map() at flowCompare/R/parameter_optimization_simple.R:3:3:ℹ In index: 11. Caused by error in pdf():

! could not open file 'C:**\AppData\Local\Temp\Rtmp6n5WXe/consensus.pdf'
Run rlang::last_trace() to see where the error occurred.

where *** is just the personal file path on my laptop.

It seems random, not constricted to certain files.

Input data are patient data, summarized in a list of dataframes. The idea is to cluster each patient/dataframe from a set range in FlowSOM() to detect the optimal hyperparameter for that clustering tool.

However, my vectorized function stops at a random file, claiming it couldn't find the consensus.pdf.

For better traceability, I generated a reprex:

library(flowCore)
library(FlowSOM)
library(purrr)
library(ggplot2)
library(smerc)

df.list <- replicate(40, as.data.frame(matrix(rnorm(2700, mean = 3, sd = 4), ncol = 9)), simplify = F )
df.list <- map(df.list, function(.y) { colnames(.y) <- paste0("C", 1:9); return(.y) } )
names(df.list) <- paste0("File",1:40)

mean_ss <- function(x) {centroid <- colMeans(x); mean(sapply(1:nrow(x), function(i) dist(rbind(x[i,], centroid))))}

calculate_median_ss <- function(dat, i, mode) {
  Cluster_ = as.numeric(GetMetaclusters(FlowSOM(input = flowFrame(dat), nClus=i, seed = 1))) 

  dfds <- data.frame(dat, Cluster_)

  clust <- table(dfds[["Cluster_"]])
  ds <- split(dfds, dfds[["Cluster_"]])
  ds <- lapply(ds, as.matrix)
  ds <- lapply(ds, mean_ss)
  ds <- unlist(ds)
  ds <- switch(mode, "median" = median(ds), "mean" = mean(ds))
  return(list(susq = ds, tab = clust))
  }

parameter_optimization_simple <- function(dat, channels, nam, smoothing, seq_x) {

  opt_plot <- map(seq_x, ~ calculate_median_ss(as.matrix(dat[channels]), .x, "mean"))

  plot.df <- data.frame( nClus = seq_x, median_ss = unlist(map(opt_plot, ~ .x[[1]])) )
  colnames(plot.df)[1] <- "nClus"

  p <- ggplot(plot.df, aes(plot.df[[1]], plot.df[[2]])) +
    labs(x = "nClus", y = "mean_ss")
  p <- switch(smoothing, "Y" = {p + geom_smooth()}, "N" = { p + geom_point() + geom_line() } )
  p <- ggplot_build(p)[[1]][[1]]

  elbow <- elbow_point(p[["x"]], p[["y"]])$x

  cat(paste("Clustering for", nam,"optimized! \n"))

  return(elbow) 
  }

channels <- paste0("C", 1:9)
seq_x <- seq(4,34,2)

set.seed(5)
opt_param_list = map2(.x = df.list, .y = names(df.list), ~ parameter_optimization_simple(.x, channels, nam = .y, smoothing = T, seq_x)) 

I have tried to remove and re-install FlowSOM, I have updated all packages and R, but still the error keeps popping up. Also, I couldn't find any pattern to when this error occurs, it seems just completely random and not reproducible.

The whole error message looks like this:

enter image description here