Empty opaque value in function call detected as list comprehension

[jklmnn]

Trying to call a function with an empty opaque value as follows:

with function Platform_Function (Data : Opaque) return Result_Type;
...
Result := Platform_Function ([]);

causes the following error:

Traceback (most recent call last):
  File "/.../RecordFlux/tests/integration/feature_test.py", line 112, in test_executability
    assert assert_executable_code(model, integration, tmp_path, main=MAIN) == config.sequence
  File "/.../RecordFlux/tests/utils.py", line 171, in assert_executable_code
    assert_compilable_code(
  File "/.../RecordFlux/tests/utils.py", line 149, in assert_compilable_code
    _create_files(tmp_path, model, integration, main, prefix, debug)
  File "/.../RecordFlux/tests/utils.py", line 271, in _create_files
    Generator(
  File "/.../RecordFlux/rflx/generator/generator.py", line 142, in generate
    units = self._generate(model, integration)
  File "/.../RecordFlux/rflx/generator/generator.py", line 265, in _generate
    units.update(self._create_session(s, integration))
  File "/.../RecordFlux/rflx/generator/generator.py", line 282, in _create_session
    session_generator = SessionGenerator(
  File "/.../RecordFlux/rflx/generator/session.py", line 188, in __init__
    self._create()
  File "/.../RecordFlux/rflx/generator/session.py", line 218, in _create
    state_machine = self._create_state_machine()
  File "/.../RecordFlux/rflx/generator/session.py", line 338, in _create_state_machine
    unit += self._create_states(self._session, composite_globals, is_global)
  File "/.../RecordFlux/rflx/generator/session.py", line 834, in _create_states
    *[
  File "/.../RecordFlux/rflx/generator/session.py", line 837, in <listcomp>
    for s in self._state_action(
  File "/.../RecordFlux/rflx/generator/session.py", line 1923, in _state_action
    result = self._assign(
  File "/.../RecordFlux/rflx/generator/session.py", line 2212, in _assign
    return self._assign_to_call(target, expression, exception_handler, is_global, state)
  File "/.../RecordFlux/rflx/generator/session.py", line 3236, in _assign_to_call
    *[a.substituted(self._substitution(is_global)).ada_expr() for a in arguments],
  File "/.../RecordFlux/rflx/generator/session.py", line 3236, in <listcomp>
    *[a.substituted(self._substitution(is_global)).ada_expr() for a in arguments],
  File "/.../RecordFlux/venv/lib/python3.9/site-packages/icontract/_checkers.py", line 641, in wrapper
    result = func(*args, **kwargs)
  File "/.../RecordFlux/rflx/expression.py", line 1797, in substituted
    expr = func(self)
  File "/.../RecordFlux/rflx/generator/session.py", line 3700, in func
    assert len(expression.elements) > 0
AssertionError