Vehicle messages fail to update after vehicle disappears

[kochman]

If a vehicle shows up on the map and then is no longer returned by /updates (due to inactivity), all vehicle messages will then fail to update after that point.

According to the console, it was not able to access the data attribute on this line:

shuttletracker/static/js/frontend.js

Line 406 in 13503e0

const update = v.ShuttlesArray[key].data;

I think this is because that value gets set to null here:

shuttletracker/static/js/frontend.js

Line 329 in 13503e0

this.ShuttlesArray[key] = null;

A possible fix could be to remove the vehicle's whole key/value from this.ShuttlesArray instead of setting its value to null when it disappears.