Python Google Geocoding API - IndexError: list index out of range?

You probably want to run a check on the types key for the address attribute you want. So try something like;

    result = data['results'][0]['address_components']
    city = ''
    country = ''

    for item in result:
        if 'administrative_area_level_1' in item[types]:
            city = item['long_name']
        elif 'country' in item[types]:
            country = item['long_name']
    return {
        'city': city,
        'country': country
    }

I think that part of the problem is that I need a check in place, in-case the API doesn't return anything for the locations.

Indeed. The first thing you want to do is to put your requests call in a try/except block to catch possible exceptions during the request phase (and there are quite a few things that can go wrong when doing an HTTP request).

BTW you don't have to build the querystring manually - requests takes care of it in a safer way (escaping etc), and you'll still have access to the resulting url in the response object if you want it. So as a starter you want:

url = 'https://maps.googleapis.com/maps/api/geocode/json'
apikey = 'API_KEY_GOES_HERE'
try:
    response = requests.get(url, params={"key":apikey, "latlng":latlng})
except requests.exceptions.RequestException as e:
    # this will log the whole traceback
    logger.exception("call failed with %s", e)
    # here you either re-raise the exception, raise your own exception,
    # or return anything
    return None

Now you also want to check the response's status code - anything else than 200 means you don't have your data

if response.status_code != 200:
    logger.error("got status code %s", response.status_code)
    # idem, either raise your own exception or
    # return anything
    return None

FWIW, response has a raise_for_status() method that will raise a RequestException if you get a 4XX or 5XX response, so you can simplify the whole thing to:

try:
    response = requests.get(url, params={"key":apikey, "latlng":latlng})
    response.raise_for_status()
except requests.exceptions.RequestException as e:
    # this will log the whole traceback
    logger.exception("call failed with %s", e)
    # here you either re-raise the exception, raise your own exception,
    # or return anything
    return None

Now you can expect you do have a valid response, so let's get our json data. Here again, requests already provides a shortcut. Note that if your response's content type is not 'application/json' or the response's content is invalid json, you'll get a ValueError but well, I think we can trust google to do the job here ;)

data = response.json()

I don't remember exactly the whole geocoding API so should really double-check the doc but IIRC as long as you got a 200, you should have some valid data.

"Why it wouldn't return anything, I have no idea."

Connection lost, API limits, server down (yes it happens), there are a lot of possible reasons. With the above code you should at least get a hint.

Now you may still not have all you expect in the resulting data - here again, check the docs, manually replay the requests for geoloc that failed and inspect the response and data etc.