Strategy for Tracking Down Gnarly Bug?

In my app, there’s an anomaly. Specifically, if I call Material-UI to set up a textfield, it draws 2 underlines under the textfield, and it’s only supposed to draw one.

I made a tiny test app, and the anomaly went away. So there’s nothing wrong with Material-UI. It’s something else in my app.

I took the routes.jsx code from the tiny test app and pasted it into my app. I also took the component code from my tiny test app and pasted that into my app. So no code is being run in my app at runtime, that wasn’t run in the tiny test app. But the anomaly is still there!

So I guess the anomaly is coming from something that happens during the build process-- does that makes sense?

Here’s the strategy I came up with. I created a new application directory and rebuilt the app, component by component, publication by publication, etc. I just copied the original code over and pasted it in the new project. I figured eventually either a) I’d add the code that brought the bug along with it or b) have a working app with now bug.

B) is what happened. I have a working application with all the original code and features, and the bug is gone.