@args --debugger --option debugger-on-warn true
Enter debugger with debugger-on-warn set.

  nix-repl> let inspect = v: builtins.warn "inspect is deprecated" (throw "this happens after"); in inspect { }

  warning: inspect is deprecated!
  warning: builtins.warn reached!

  nix-repl> :c

  { }
  error: this happens after