Currenty, the polyfill depends on the existence of the ngDevMode variable in several places to decide whether it should throw useful error messages. This is obviously a copy-paste artifact from the Angular signals codebase.

Looks like the variable should be renamed to something framework-agnostic, like signal-polyfill-debug, and its usage should be documented in the README. Otherwise, any mentions of ngDevMode could be removed altogether, and the debug messages could just always be printed.

I'd be willing to make a PR for that if needed.