The editor needs to help more before the run, not after

Right now the loop is: write something, run it, find out it wasn't what I meant. Most of my mistakes are catchable before running, a name that doesn't exist, a condition that can never be true, a missing guard. The information to catch them exists at write time. The team's already fixing the unknown-name case. I'd extend the principle: anything the system could know is wrong before the run should be said before the run. Feedback after a five-minute backtest is much more expensive than feedback while typing.