IndexError: list index out of range
(1 additional frame(s) were not displayed)
...
  File "galaxy/tools/__init__.py", line 2594, in _execute
    return self.tool_action.execute(
  File "galaxy/tools/actions/model_operations.py", line 121, in execute
    self._produce_outputs(
  File "galaxy/tools/actions/model_operations.py", line 160, in _produce_outputs
    tool.produce_outputs(
  File "galaxy/tools/__init__.py", line 4061, in produce_outputs
    _handle_paired(element)
  File "galaxy/tools/__init__.py", line 4047, in _handle_paired
    paired_datasets.append(copied_value.elements[1].element_object)

Exception caught while attempting to execute tool with id '__SPLIT_PAIRED_AND_UNPAIRED__':