If set to true, builtins.warn will throw an error when logging a warning. This will give you a stack trace that leads to the location of the warning. This is useful for finding information about warnings in third-party Nix code when you can not start the interactive debugger, such as when Nix is called from a non-interactive script. See debugger-on-warn. Currently, a stack trace can only be produced when the debugger is enabled, or when evaluation is aborted.