422 Error When Using External Geocoder and Mapbox GL JS

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1. I am using an external geocoder with the Mapbox geocoder widget.
2. The results return and are concatenated to the standard geocoder results correctly.
3. When clicking on a result in the geocoder tool menu, it navigates correctly to the point identified in the list.
4. *It also throws a 422 error, and I am not sure why.*

This is the code where I implement it:

```js
externalGeocoder: async (queryString) => {
const filters = {
geom_column: 'geom',
filter: `cast(busstopid as text) like '${queryString}%' or address like upper('${queryString}%')`,
precision: 9,
columns: 'address as place_name, address as text, busstopid',
id_column: 'internal_id',
limit: 5,
};
// get data from both the GTFS feed and MIIPS if possible
const generalData = await utilities.getData(`${URL.base}/v1/geojson/gtfs_data?`, filters);
const miipsData = await utilities.getData(
`${URL.base}/mama/miips/read_serial_number_geocoder/${queryString}`
);

if (miipsData.features) {
return generalData.features.concat(miipsData.features);
} else {
return generalData.features;
}
}
```

This is the object the external geocoder is creating:

```json
{
"type": "FeatureCollection",
"features": [
{
"id": 13419,
"type": "Feature",
"center": [
-73.94012,
40.765427
],
"geometry": {
"type": "Point",
"coordinates": [
-73.94012,
40.765427
]
},
"place_name": "34 AV/VERNON BL",
"properties": {
"text": "34 AV/VERNON BL",
"busstopid": 552207,
"place_name": "34 AV/VERNON BL"
}
},
{
"id": 14304,
"type": "Feature",
"center": [
-74.107189,
40.671472
],
"geometry": {
"type": "Point",
"coordinates": [
-74.107189,
40.671472
]
},
"place_name": "34 ST/HOBOKEN LIGHT RAIL STATION",
"properties": {
"text": "34 ST/HOBOKEN LIGHT RAIL STATION",
"busstopid": 805054,
"place_name": "34 ST/HOBOKEN LIGHT RAIL STATION"
}
},
{
"id": 14305,
"type": "Feature",
"center": [
-74.10723,
40.671416
],
"geometry": {
"type": "Point",
"coordinates": [
-74.10723,
40.671416
]
},
"place_name": "34 ST/HOBOKEN LIGHT RAIL STATION",
"properties": {
"text": "34 ST/HOBOKEN LIGHT RAIL STATION",
"busstopid": 805056,
"place_name": "34 ST/HOBOKEN LIGHT RAIL STATION"
}
}
]
}
```

I looked into the repo and tried to discern from the error and payload what I was doing wrong. The results seem to work correctly, but it also seems like it is trying to use the external result with the standard geocoder somehow, which seems wrong. I am not sure how to drill down into this further to better diagnose the behavior, but any help would be most appreciated.

Start with the externalGeocoder callback and the supplied FeatureCollection, then trace the result-selection path used when a returned feature is clicked. Reproduce the 422 with the shown payload and inspect whether selection also invokes the standard geocoder request. Done means identifying the request causing the 422 and documenting or correcting the handling of external results.

Written by the indexing model from the issue text.