[24.0] Don't fail if reporting invalid parameter values

[mvdbeek]

which can contain None values.
Fixes the following traceback:

TypeError: sequence item 0: expected str instance, NoneType found
  File "galaxy/web/framework/decorators.py", line 346, in decorator
    rval = func(self, trans, *args, **kwargs)
  File "galaxy/webapps/galaxy/api/tools.py", line 247, in build
    return tool.to_json(trans, kwd.get("inputs", kwd), history=history)
  File "galaxy/tools/__init__.py", line 2509, in to_json
    populate_state(request_context, self.inputs, params.__dict__, state_inputs, state_errors)
  File "galaxy/tools/parameters/__init__.py", line 412, in populate_state
    _populate_state_legacy(
  File "galaxy/tools/parameters/__init__.py", line 625, in _populate_state_legacy
    check_param(request_context, input, param_value, context, simple_errors=simple_errors)
  File "galaxy/tools/parameters/__init__.py", line 246, in check_param
    value = param.from_json(value, trans, param_values)
  File "galaxy/tools/parameters/basic.py", line 1045, in from_json
    f"invalid options ({','.join(set(value) - set(legal_values))!r}) were selected (valid options: {','.join(legal_values)})",

Where None was in values. Note also that pyright underlined these lines, not sure why mypy has ignored this error.

Partial fix for #18001

How to test the changes?

(Select all options that apply)

• I've included appropriate automated tests.
• This is a refactoring of components with existing test coverage.
• Instructions for manual testing are as follows:
  1. [add testing steps and prerequisites here if you didn't write automated tests covering all your changes]

License

• I agree to license these and all my past contributions to the core galaxy codebase under the MIT license.