Elixir.MatchError for nil OpenAQ measurement results

[Niklas Long]

https://sentry.io/simplabs/ppm-server/issues/552262233/

Elixir.MatchError: no match of right hand side value: %{"meta" => %{"found" => 0, "license" => "CC BY 4.0", "limit" => 100, "name" => "openaq-api", "page" => 1, "website" => "https://docs.openaq.org/"}, "results" => []}
  File "lib/airquality/sources/open_aq/measurements.ex", line 43, in Airquality.Sources.OpenAQ.Measurements.query_open_aq/1
  File "lib/airquality/sources/open_aq/measurements.ex", line 7, in Airquality.Sources.OpenAQ.Measurements.get_latest/1
  File "lib/airquality_web/controllers/measurement_controller.ex", line 8, in AirqualityWeb.MeasurementController.index/2
  File "lib/airquality_web/controllers/measurement_controller.ex", line 1, in AirqualityWeb.MeasurementController.action/2
  File "lib/airquality_web/controllers/measurement_controller.ex", line 1, in AirqualityWeb.MeasurementController.phoenix_controller_pipeline/2
...
(3 additional frame(s) were not displayed)

(MatchError) no match of right hand side value: %{"meta" => %{"found" => 0, "license" => "CC BY 4.0", "limit" => 100, "name" => "openaq-api", "page" => 1, "website" => "https://docs.openaq.org/"}, "results" => []}