return<

The app stopped working and said nothing about it. No error. No red text. No stack trace pointing at a line. It did the thing a minute ago and now it didn't, and the console was clean the whole time.

The cause was a missing space.

Somewhere in a build step, the JSX got compressed, and the compression stripped the space after a return. So return <div became return<div, and return< doesn't read the way you'd think. The parser doesn't see a keyword followed by markup. It sees return butted against a less-than, and it interprets that seam differently than the code you wrote. The statement stops meaning what it meant. No syntax error, because it's still technically parseable. Just wrong, and silent about it.

One instance would have been a bad afternoon. There were twelve. The same compression had eaten the same space in twelve places across the codebase, each one a small silent break, none of them announcing itself.

The Fix Was One Line

Twelve broken statements. One sed command. Find the pattern, restore the space, done, a single line of the terminal fixing all twelve at once, faster than it took to find the first one.

That's the part worth sitting with. The repair was trivial. The repair is almost always trivial once you know what you're repairing. What cost the time was the distance between "something is wrong" and "here is the character that's wrong", a gap the tool gave me no help closing, because from its perspective nothing was wrong at all. The code parsed. The build succeeded. The indicator was green over an app that didn't run.

Some bugs are complexity. You earn those; they're a real problem wearing its real size. This wasn't that. This was a single absent space, multiplied by twelve, hiding behind a build process that thought it had done its job.

The bug was never complicated. Finding it was the entire job.