Extractor requires a URL or a FeroxResponse be specified as…

Error message

Extractor requires a URL or a FeroxResponse be specified as well as a Handles object

What it means

ExtractorBuilder::build requires either a URL (with_url) or a FeroxResponse (with_response) plus a Handles object; otherwise no extractor can be constructed since there is nothing to scrape links from and no configuration context.

Solutions

Chain .with_url(&url) (or .with_response(&response)) before build()
Chain .with_handles(handles.clone()) before build()
Verify the builder call chain compiles to include both a source (url/response) and handles

Example fix

// before
let extractor = ExtractorBuilder::default().build()?;
// after
let extractor = ExtractorBuilder::default()
    .with_url("https://example.com")
    .with_handles(handles.clone())
    .build()?;

Defensive patterns

Strategy: validation

Validate before calling

fn builder_ready(url: &str, response: Option<&FeroxResponse>, handles: Option<Handles>) -> bool {
    (!url.is_empty() || response.is_some()) && handles.is_some()
}
if !builder_ready(&url, response.as_ref(), handles) {
    return Err("extractor needs url or response, plus handles".into());
}

Type guard

fn has_handles(h: &Option<Handles>) -> bool { h.is_some() }

Try / catch

let extractor = builder.build().map_err(|e| {
    eprintln!("builder incomplete: {e}; did you forget with_url/with_response or with_handles?");
    e
})?;

Prevention

Chain with_url or with_response and with_handles in the same builder expression
Prefer builder methods over ExtractorBuilder::default() to avoid incomplete states
Add a unit test that builds an extractor the way production code does

When it happens

Trigger: Calling build() without having chained with_url()/with_response(), or without with_handles() — e.g. a builder created with ExtractorBuilder::default() and immediately built.

Common situations: Refactors dropping a builder method call; copy-pasted builder code missing with_url when switching from response-based to URL-based extraction; forgetting with_handles after changing constructor signatures across versions.

Understand the failure class

Background: "missing required argument" and "the following required arguments were not provided": what required-argument errors mean and how to fix them — this error's family across 20 libraries.

AI-assisted analysis of epi052/feroxbuster@1f595dab5c (2026-09-13). Data as JSON: /api/errors/a6bd590ed38e89ea. Report an issue: GitHub.

Appendix: source

Thrown at src/extractor/builder.rs:132

    /// builder call to set `target`
    pub fn target(&mut self, target: ExtractionTarget) -> &mut Self {
        self.target = target;
        self
    }

    /// builder call to set `response`
    pub fn response(&mut self, response: &'a FeroxResponse) -> &mut Self {
        self.response = Some(response);
        self
    }

    /// finalize configuration of `ExtractorBuilder` and return an `Extractor`
    ///
    /// requires either `with_url` or `with_response` to have been used in the build process
    pub fn build(&self) -> Result<Extractor<'a>> {
        if (self.url.is_empty() && self.response.is_none()) || self.handles.is_none() {
            bail!("Extractor requires a URL or a FeroxResponse be specified as well as a Handles object")
        }

        Ok(Extractor {
            links_regex: Regex::new(LINKFINDER_REGEX).unwrap(),
            robots_regex: Regex::new(ROBOTS_TXT_REGEX).unwrap(),
            url_regex: Regex::new(URL_CHARS_REGEX).unwrap(),
            response: self.response,
            url: self.url.to_owned(),
            handles: self.handles.as_ref().unwrap().clone(),
            target: self.target,
        })
    }
}

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