Running examples in ‘mlr3fairness-Ex.R’ failed
The error most likely occurred in:

> ### Name: fairness_accuracy_tradeoff
> ### Title: Plot Fairness Accuracy Trade-offs
> ### Aliases: fairness_accuracy_tradeoff
> 
> ### ** Examples
> 
> ## Don't show: 
> if (rlang::is_installed("rpart") && rlang::is_installed("ranger")) (if (getRversion() >= "3.4") withAutoprint else force)({ # examplesIf
+ ## End(Don't show)
+ library("mlr3")
+ library("mlr3learners")
+ library("ggplot2")
+ 
+ # Setup the Fairness measure and tasks
+ task = tsk("adult_train")$filter(1:500)
+ learner = lrn("classif.ranger", predict_type = "prob")
+ fairness_measure = msr("fairness.tpr")
+ 
+ # Example 1 - A single prediction
+ learner$train(task)
+ predictions = learner$predict(task)
+ fairness_accuracy_tradeoff(predictions, fairness_measure, task = task)
+ 
+ # Example2 - A benchmark
+ design = benchmark_grid(
+   tasks = task,
+   learners = lrns(c("classif.featureless", "classif.rpart"),
+     predict_type = "prob", predict_sets = c("train", "test")),
+   resamplings = rsmps("cv", folds = 2)
+ )
+ bmr = benchmark(design)
+ fairness_accuracy_tradeoff(bmr, fairness_measure)
+ ## Don't show: 
+ }) # examplesIf
> library("mlr3")
> library("mlr3learners")
> library("ggplot2")
> task = tsk("adult_train")$filter(1:500)
> learner = lrn("classif.ranger", predict_type = "prob")
> fairness_measure = msr("fairness.tpr")
> learner$train(task)
> predictions = learner$predict(task)
> fairness_accuracy_tradeoff(predictions, fairness_measure, task = task)
> design = benchmark_grid(tasks = task, learners = lrns(c("classif.featureless", 
+     "classif.rpart"), predict_type = "prob", predict_sets = c("train", "test")), 
+     resamplings = rsmps("cv", folds = 2))
> bmr = benchmark(design)
INFO  [12:29:47.604] [mlr3] Running benchmark with 4 resampling iterations
INFO  [12:29:48.169] [mlr3] Applying learner 'classif.featureless' on task 'adult_train' (iter 1/2)
INFO  [12:29:48.379] [mlr3] Applying learner 'classif.featureless' on task 'adult_train' (iter 2/2)
INFO  [12:29:48.530] [mlr3] Applying learner 'classif.rpart' on task 'adult_train' (iter 1/2)
INFO  [12:29:48.705] [mlr3] Applying learner 'classif.rpart' on task 'adult_train' (iter 2/2)
INFO  [12:29:48.827] [mlr3] Finished benchmark
Error in `[.data.table`(data, , `:=`("task_hash", task[[1L]]$hash), by = "uhash") : 
  attempt access index 9/9 in VECTOR_ELT
Calls: <Anonymous> ... initialize -> .__ResultData__initialize -> [ -> [.data.table
Execution halted