I’m getting a prod only build error that wasn’t very helpful with no line numbers and an error thrown deep in terser.
This error for me turned out to be unsupported handling of the new Optional Chaining operator (foo?.) — make sure if you’re using it your bundler configurations are handling said feature.
In my case I’m using a node environment set up by what looks like a Contentful UI Extension starter app, so I don’t want to modify any build configurations. I just removed it and moved on.
Yuji Tomita 