Chrome DevTools won't let me set breakpoints on certain lines

Question

In the image above, I tried setting breakpoints on every line from line 437 to line 443. However, I cannot set breakpoints on lines 439 and 440. When the function runs,

Answer 1

This was frustrating for me today but I found the problem. I was trying to place a breakpoint inside an orphan function (nothing was calling it). As soon as I fixed it, all was well. Smart - but wish there was even a tiny hint that this was the case.