What differences exist in error metadata between `pug.render` and `pug.renderFile` when `filename` is omitted?
The filename option in Pug is documented as necessary for resolving include and extends directives and for attaching template location information to error objects, yet the parameter is optional in the public API. This omission triggers divergent fallback behaviors depending on whether pug.render or pug.renderFile is used, particularly when templates employ