Bug - The conf.ini value MODEL_SETTINGS_FILE, can override oasislmf.json. even if set to None.

[sambles]

Issue Description

If MODEL_SETTINGS_FILE is set to a path that doesn't exist, then the following line is set to model_settings_file = None

OasisPlatform/src/model_execution_worker/tasks.py

Lines 303 to 305 in a585706

	# model settings
	model_settings_fp = settings.get('worker', 'MODEL_SETTINGS_FILE', fallback='')
	model_settings_file = model_settings_fp if model_settings_fp and os.path.isfile(model_settings_fp) else None

OasisPlatform/src/model_execution_worker/tasks.py

Lines 307 to 311 in a585706

	task_params = {
	'oasis_files_dir': oasis_files_dir,
	'model_run_dir': run_dir,
	'analysis_settings_json': analysis_settings_file,
	'model_settings_json': model_settings_file,

That value is then stored in a dict, which is later combined with the oasislmf.json contents.

OasisPlatform/src/model_execution_worker/tasks.py

Lines 346 to 348 in a585706

	# Create and log params
	run_params = {**config, **task_params}
	gen_losses_params = OasisManager()._params_generate_oasis_losses(**run_params)

Which can override a valid model_settings_json path with None:

In [1]: oasislmf_config = {'model_settings_json': "some-valid-path"}
In [2]: task_params = {'model_settings_json': None}
In [3]: run_params = {**oasislmf_config, **task_params}
In [4]: run_params
Out[4]: {'model_settings_json': None}