^^^ Exactly, what's a big deal ? Xcode that was bundled with the OS update is flawed, Getting the fresh one directly fixes it.

Found it, among dozens of thousands of code there was this line: const re = /(?=\()([^)]+)(?=\))/g; It was not executed but apparently was being evaluatedbefore the main entry point got called, That's why no debugger could get to it.