ICE plots - Error in guess(varying) about homlr HOT 3 CLOSED

# packages required
library(ranger)
library(rsample)
library(pdp)

# data
attrition <- rsample::attrition %>% 
  mutate_if(is.ordered, factor, ordered = FALSE) %>%
  mutate(Attrition = relevel(Attrition, ref = "Yes"))

# Create training and testing sets
set.seed(123)
split <- initial_split(attrition, prop = .8, strata = "Attrition")
attrit_train <- training(split)
attrit_test  <- testing(split)

# probability model
m3_ranger_prob <- ranger(
  formula         = Attrition ~ ., 
  data            = attrit_train, 
  num.trees       = 250,
  mtry            = 25,
  respect.unordered.factors = 'order',
  verbose         = FALSE,
  seed            = 123,
  min.node.size   = 1,
  sample.fraction = .80,
  probability     = TRUE,
  importance      = 'impurity'
  )

# custom ICE prediction function
custom_pred <- function(object, newdata) {
  pred <- predict(object, newdata)
  avg <- pred$predictions[, 1]
  return(avg)
}

# compute and plot ICE curves
m3_ranger_prob %>%
  partial(pred.var = "OverTime", ice = TRUE, center = TRUE, pred.fun = custom_pred, train = attrit_train) %>%
  autoplot(rug = TRUE, train = attrit_train, alpha = 0.2)

# custom prediction function
custom_pred <- function(object, newdata) {
  pred <- predict(object, newdata)
  avg <- mean(pred$predictions[, 1]) 
  return(avg)
}

# custom prediction function
custom_pred <- function(object, newdata) {
  pred <- predict(object, newdata)
  avg <- pred$predictions[, 1]
  return(avg)
}