Not sure if this counts for WTH or is considered an FR.
I often find it hard to track down the source of errors in an automation, especially if you are writing a blueprint. A proper debug routine with breakpoints, step by step execution and tracing, automatic highlighting of expressions that lead to errors etc would be a great help.
In addition, how about actual line numbers and file names for errors in the yaml configuration? If you use !includes to organize large configurations, it’s very difficult to track down error locations.