For loop in action creator : "Actions must be plain objets. Use custom middleware for async actions"

Question

I'm having this error even though everything seems to return an action in my action creator. I have to use a for loop to make a request for every item in my array. It looks like my Promise.all is not working, maybe?

Any ideas?

index.js

const store = createStore(
    allReducers,
    compose(
        applyMiddleware(thunk),
        window.__REDUX_DEVTOOLS_EXTENSION__ && window.__REDUX_DEVTOOLS_EXTENSION__()
    )
);

actions.js

export const searchPeople = (clientAdress, skill, collaborators) => {
  const filteredCollabs = collaborators.filter(collab => collab.skills.includes(skill));
  let collab;
  let origin = "";
  let mode = "";
  let promises = [];
  for (let i = 0; i < filteredCollabs.length; i++) {
    collab = filteredCollabs[i];
    origin = `${filteredCollabs[i].latitude},${filteredCollabs[i].longitude}`;
    mode = `${filteredCollabs[i].mode}`;
    let promise = dispatch => axios
      .get(`https://maps.googleapis.com/maps/api/distancematrix/json?origins=${origin}&destinations=${clientAdress}&region=FR&mode=${mode}&key=${config.gmap.key}`)
      .then(response => dispatch({
        type: "SET_DURATION",
        collab,
        duration: response.data.rows[0].elements[0].duration.text
      }))
      .catch(err => dispatch({
        type: "ERROR",
        err,
      }));
    promises.push(promise);
  }

  function everythingIsDone() {
    return dispatch => Promise.all(promises)
      .then(values => dispatch({
        type: "DONE",
        values
      }))
      .catch(err => dispatch({
        type: "ERROR",
        err
      }))
  }

  everythingIsDone();
}

Thanks a lot in advance!