Add `String.safeToString_` static method that tracks objects currently being converted to string per fiber, returning "..." when recursion is detected. Wrap List.toString and Map.toString with this guard to handle self-referential and mutually recursive structures without crashing.
The Wren scripts in this directory get converted to C string literals and then inserted into their respective .c files so that the interpreter can load them directly without having to do any file IO.
The script that does this copying is script/generate_builtins.py.
You can invoke using make builtin.