Ensure at least one output type specified as required when a modeling task contains a required target

[annakrystalli]

If not it creates a problem down the line when hubData::expand_model_out_val_grid() is run with required_vals_only = TRUE.

e.g. with the following example config:

{
    "schema_version": "https://raw.githubusercontent.com/Infectious-Disease-Modeling-Hubs/schemas/main/v2.0.0/tasks-schema.json",
    "rounds": [
	{
            "round_id_from_variable": true,
            "round_id": "origin_date",
            "model_tasks": [
            {
               	"task_ids": {
                    "origin_date": {
                        "required": null,
                        "optional": [
                            "2023-11-12", "2023-11-19", "2023-11-26"
                            ]
                    },
                    "target": {
                        "required": null,
                        "optional": ["inc hosp"]
                    },
                    "horizon": {
                        "required": [1, 2],
                        "optional": [0]
                    },
                    "location": {
                        "required": null,
                        "optional": [
                                "US",
                                "01",
                                "02"
                            ]
                    },
                    "age_group":{
                        "required":["0-130"],
                        "optional":["0-0.99","1-4","5-17","5-64","18-49","50-64","65-130"]
		            }
                },
                "output_type": {
                    "quantile":{
                        "output_type_id":{
                            "required": [
                                0.01,
                                0.025,
                                0.05,
                                0.1,
                                0.15,
                                0.2,
                                0.25,
                                0.3,
                                0.35,
                                0.4,
                                0.45,
                                0.5,
                                0.55,
                                0.6,
                                0.65,
                                0.7,
                                0.75,
                                0.8,
                                0.85,
                                0.9,
                                0.95,
                                0.975,
                                0.99
                            ],
                            "optional":null
                        },
			            "value":{
	   		                "type":"double",
	   		                "minimum":0

			            }
                    }
                },
                "target_metadata": [
                    {
                       "target_id": "inc hosp",
                       "target_name": "Weekly incident RSV hospitalizations",
                       "target_units": "count",
                       "target_keys": {
                           "target": ["inc hosp"]
                       },
                       "target_type": "continuous",
                       "is_step_ahead": true,
                       "time_unit": "week"
                    }
                ]
		    },
            {
                "task_ids": {
                 "origin_date": {
                     "required": null,
                     "optional": [
                         "2023-11-12", "2023-11-19", "2023-11-26"
                         ]
                 },
                 "target": {
                     "required": ["peak time hosp"],
                     "optional": null
                 },
                 "horizon": {
                     "required": null,
                     "optional": null
                 },
                 "location": {
                     "required": null,
                     "optional": [
                             "US",
                             "01",
                             "02"
                         ]
                 },
                 "age_group":{
                     "required":["0-130"],
                     "optional":["0-0.99","1-4","5-17","5-64","18-49","50-64","65-130"]
                 }
                },
                "output_type": {
                    "cdf":{
                        "output_type_id":{
                            "required":null,
                            "optional":[1]
                        },
                        "value":{
                            "type":"double",
                            "minimum":0,
                            "maximum":1
                        }
                    }
                },
                "target_metadata": [
                 {
                    "target_id": "peak time hosp",
                    "target_name": "Peak timing of hospitalization",
                    "target_units": "population",
                    "target_keys": {
                        "target": ["peak time hosp"]
                    },
                    "target_type": "discrete",
                    "is_step_ahead": true,
                    "time_unit": "week"
                 }
                ]
            }
		],
       	"submissions_due": {
            "relative_to": "origin_date",
            "start": -6,
            "end": 100
        }
    }
    ]
}

The following error is returned:

Error in `purrr::map()` at hubData/R/expand_model_out_val_grid.R:199:5:
ℹ In index: 2.
Caused by error in `value[[jvseq[[jjj]]]]`:
! subscript out of bounds
Run `rlang::last_trace()` to see where the error occurred.

from:

hubData::expand_model_out_val_grid(
  config_tasks,
  round_id = "2023-11-26",
  required_vals_only = TRUE
)

because the second modeling task has a required target but no required output type:

[annakrystalli]

Perhaps we should also handle this exception somehow in the hubData::expand_model_out_val_grid()?