Widgets fail with a dataset with hidden variables on the input.

[PrimozGodec]

Description

Some widgets fail when a dataset with hidden variables at the input. It can be reproduced with data from the Image Embedding widget. Currently, the following widgets are discovered to fail:

• Scatter Plot fail when I use Find informative projections, including hidden variables. It fails when I click on a combination that includes the hidden variable. See screenshot. My suggestion is to exclude hidden variables from the informative projections search.
  

• Group By fail immediately when I connect the data with hidden variables.

      Traceback (most recent call last):
        File "/Users/primoz/python-projects/orange-canvas-core/orangecanvas/scheme/signalmanager.py", line 1047, in __process_next
          if self.__process_next_helper(use_max_active=True):
        File "/Users/primoz/python-projects/orange-canvas-core/orangecanvas/scheme/signalmanager.py", line 1085, in __process_next_helper
          self.process_node(selected_node)
        File "/Users/primoz/python-projects/orange-canvas-core/orangecanvas/scheme/signalmanager.py", line 713, in process_node
          self.send_to_node(node, signals_in)
        File "/Users/primoz/miniconda3/envs/orange3/lib/python3.10/site-packages/orangewidget/workflow/widgetsscheme.py", line 806, in send_to_node
          self.process_signals_for_widget(node, widget, signals)
        File "/Users/primoz/miniconda3/envs/orange3/lib/python3.10/site-packages/orangewidget/workflow/widgetsscheme.py", line 820, in process_signals_for_widget
          process_signals_for_widget(widget, signals, workflow)
        File "/Users/primoz/miniconda3/envs/orange3/lib/python3.10/functools.py", line 889, in wrapper
          return dispatch(args[0].__class__)(*args, **kw)
        File "/Users/primoz/miniconda3/envs/orange3/lib/python3.10/site-packages/orangewidget/workflow/widgetsscheme.py", line 921, in process_signals_for_widget
          process_signal_input(input_meta, widget, signal, workflow)
        File "/Users/primoz/miniconda3/envs/orange3/lib/python3.10/functools.py", line 889, in wrapper
          return dispatch(args[0].__class__)(*args, **kw)
        File "/Users/primoz/miniconda3/envs/orange3/lib/python3.10/site-packages/orangewidget/workflow/widgetsscheme.py", line 884, in process_signal_input_default
          notify_input_helper(
        File "/Users/primoz/miniconda3/envs/orange3/lib/python3.10/functools.py", line 889, in wrapper
          return dispatch(args[0].__class__)(*args, **kw)
        File "/Users/primoz/miniconda3/envs/orange3/lib/python3.10/site-packages/orangewidget/utils/signals.py", line 692, in set_input_helper
          handler(*args)
        File "/Users/primoz/miniconda3/envs/orange3/lib/python3.10/site-packages/orangewidget/utils/signals.py", line 205, in summarize_wrapper
          method(widget, value)
        File "/Users/primoz/python-projects/orange3/Orange/widgets/data/owgroupby.py", line 493, in set_data
          self._set_gb_selection()
        File "/Users/primoz/python-projects/orange3/Orange/widgets/data/owgroupby.py", line 534, in _set_gb_selection
          index = values.index(val)
      ValueError: ContinuousVariable(name='n0', number_of_decimals=3) is not in list
  

• We should also test other widgets using hidden variables - it seems to be OK

AttributeList issue - @janezd's comment:

• Scatter Plot - Fails when hidden features are on input. Fixed in [FIX] Scatter Plot - Handle input features that are hidden in data #6531
• Siewe - Do not fail, but the plot is present. It would be better without a plot since the plot does show input features.
• Aggregate Columns

[janezd]

Also check widgets that accept AttributeList.