fix: remove task prototype when resample (#981)

* refactor: remove task prototype when resample

* refactor: add option to store prototype

* fix: braket

* refactor: null

* fix: browser

* keep prototypes in state when store_models is TRUE

* refactor: only store data_prototype when train

* refactor: feature names

---------

Co-authored-by: Sebastian Fischer <sebf.fischer@gmail.com>

R/Learner.R

@@ -244,6 +244,11 @@ Learner = R6Class("Learner",
 
       learner_train(learner, task, train_row_ids = train_row_ids, test_row_ids = test_row_ids, mode = mode)
 
+      # store data prototype
+      proto = task$data(rows = integer())
+      self$state$data_prototype = proto
+      self$state$task_prototype = proto
+
       # store the task w/o the data
       self$state$train_task = task_rm_backend(task$clone(deep = TRUE))
 

R/worker.R

@@ -68,15 +68,13 @@ learner_train = function(learner, task, train_row_ids = NULL, test_row_ids = NUL
   log = append_log(NULL, "train", result$log$class, result$log$msg)
   train_time = result$elapsed
 
-  proto = task$data(rows = integer())
   learner$state = insert_named(learner$state, list(
     model = result$result,
     log = log,
     train_time = train_time,
     param_vals = learner$param_set$values,
     task_hash = task$hash,
-    data_prototype = proto,
-    task_prototype = proto,
+    feature_names = task$feature_names,
     mlr3_version = mlr_reflections$package_version
   ))