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

I think that my classmate and I had this issue as well today. We made our changes and then hit Ctrl + S (or Cmd + S) to save the changes in the debugger and then we were able to add the breakpoints.