Fix divide by zero in updates dashboard

grafana/dashboards/updates.json

@@ -571,7 +571,7 @@
           "group": [],
           "metricColumn": "none",
           "rawQuery": true,
-          "rawSql": "with u as (\r\n  select *, coalesce(lag(start_date) over(order by start_date desc), now()) as next_start_date \r\n  from updates\r\n  where car_id = $car_id and $__timeFilter(start_date)\r\n),\r\nrng as (\r\n  SELECT\r\n\t  to_timestamp(floor(extract(epoch from date)/21600)*21600) AS date,\r\n\t  (sum([[preferred_range]]_battery_range_km) / sum(coalesce(usable_battery_level,battery_level)) * 100 ) AS \"battery_rng\"\r\n  FROM (\r\n    select battery_level, usable_battery_level, date, rated_battery_range_km, ideal_battery_range_km\r\n    from positions\r\n    where car_id = $car_id and $__timeFilter(date) and ideal_battery_range_km is not null\r\n    union all\r\n    select battery_level, coalesce(usable_battery_level,battery_level) as usable_battery_level, date, rated_battery_range_km, ideal_battery_range_km\r\n    from charges c\r\n    join charging_processes p ON p.id = c.charging_process_id \r\n    where $__timeFilter(date) and p.car_id = $car_id\r\n  ) as data\r\n  GROUP BY 1\r\n)\r\n\r\nselect\t\r\n  u.start_date as time,\r\n\textract(EPOCH FROM u.end_date - u.start_date) AS update_duration,\r\n\textract(EPOCH FROM u.start_date - lag(u.start_date) OVER (ORDER BY u.start_date)) AS since_last_update,\r\n\tsplit_part(u.version, ' ', 1) as version,\r\n\tcount(distinct cp.id) as chg_ct,\r\n\tconvert_km(avg(r.battery_rng), '$length_unit')::numeric(6,2) AS avg_[[preferred_range]]_range_[[length_unit]]\r\nfrom u u\r\nleft join charging_processes cp\r\n\tON u.car_id = cp.car_id\r\n \tand cp.start_date between u.start_date and u.next_start_date\r\nleft join rng r\r\n\tON r.date between u.start_date and u.next_start_date\r\ngroup by u.car_id,\r\n\tu.start_date,\r\n\tu.end_date,\r\n\tnext_start_date,\r\n\tsplit_part(u.version, ' ', 1)",
+          "rawSql": "with u as (\r\n  select *, coalesce(lag(start_date) over(order by start_date desc), now()) as next_start_date \r\n  from updates\r\n  where car_id = $car_id and $__timeFilter(start_date)\r\n),\r\nrng as (\r\n  SELECT\r\n\t  to_timestamp(floor(extract(epoch from date)/21600)*21600) AS date,\r\n\t  (sum([[preferred_range]]_battery_range_km) / nullif(sum(coalesce(usable_battery_level,battery_level)),0) * 100 ) AS \"battery_rng\"\r\n  FROM (\r\n    select battery_level, usable_battery_level, date, rated_battery_range_km, ideal_battery_range_km\r\n    from positions\r\n    where car_id = $car_id and $__timeFilter(date) and ideal_battery_range_km is not null\r\n    union all\r\n    select battery_level, coalesce(usable_battery_level,battery_level) as usable_battery_level, date, rated_battery_range_km, ideal_battery_range_km\r\n    from charges c\r\n    join charging_processes p ON p.id = c.charging_process_id \r\n    where $__timeFilter(date) and p.car_id = $car_id\r\n  ) as data\r\n  GROUP BY 1\r\n)\r\n\r\nselect\t\r\n  u.start_date as time,\r\n\textract(EPOCH FROM u.end_date - u.start_date) AS update_duration,\r\n\textract(EPOCH FROM u.start_date - lag(u.start_date) OVER (ORDER BY u.start_date)) AS since_last_update,\r\n\tsplit_part(u.version, ' ', 1) as version,\r\n\tcount(distinct cp.id) as chg_ct,\r\n\tconvert_km(avg(r.battery_rng), '$length_unit')::numeric(6,2) AS avg_[[preferred_range]]_range_[[length_unit]]\r\nfrom u u\r\nleft join charging_processes cp\r\n\tON u.car_id = cp.car_id\r\n \tand cp.start_date between u.start_date and u.next_start_date\r\nleft join rng r\r\n\tON r.date between u.start_date and u.next_start_date\r\ngroup by u.car_id,\r\n\tu.start_date,\r\n\tu.end_date,\r\n\tnext_start_date,\r\n\tsplit_part(u.version, ' ', 1)",
           "refId": "A",
           "select": [
             [