Unwrap Police

"thread fl2_worker_thread panicked: called Result::unwrap() on an Err value"

— Cloudflare, November 18, 2025

A VS Code extension that highlights every .unwrap() call in your Rust code with aggressive red styling. Because sometimes the best way to prevent production incidents is to make dangerous operations impossible to ignore.

Background

On November 18, 2025, Cloudflare experienced a major outage affecting their core CDN and security services. The root cause? A single unwrap() call in their FL2 proxy's Rust implementation that panicked when it encountered an unexpectedly large configuration file.

The incident lasted nearly 6 hours and impacted multiple critical services including Workers KV, Access authentication, and their main dashboard. All because one Result::unwrap() wasn't replaced with proper error handling.

This extension exists as a gentle reminder that unwrap() in production code is a time bomb waiting for the right conditions to detonate.

Features

• Aggressive Visual Highlighting: Every .unwrap() gets a red background and red text
• Smart Detection: Ignores .unwrap() in comments (unlike production systems that ignore error handling)
• Real-time Counting: Status bar shows the exact number of potential panic points in your file
• Hover Warnings: Mouse over any .unwrap() to see a friendly reminder about what happened to Cloudflare
• Zero Configuration: Works out of the box, because sometimes the best config is no config

Installation

From VS Code Marketplace (Recommended)

1. Open VS Code
2. Press Ctrl+Shift+X (or Cmd+Shift+X on macOS) to open Extensions
3. Search for "Unwrap Police"
4. Click Install

Or install directly from the VS Code Marketplace.

From Command Line

code --install-extension rxliuli.unwrap-police

From Source

git clone https://github.com/rxliuli/unwrap-police.git
cd unwrap-police
pnpm install
pnpm build

Then press F5 in VS Code to launch the extension in debug mode.

Usage

1. Open any Rust file (.rs)
2. Watch in horror as your .unwrap() calls light up like a Christmas tree
3. Consider using ?, unwrap_or(), unwrap_or_else(), or expect() with meaningful error messages
4. Sleep better at night knowing your code won't take down your infrastructure

What This Extension Does NOT Do

• It won't fix your code
• It won't prevent you from deploying unwraps
• It won't save you from configuration errors
• It won't implement proper error handling for you

Those are your job.

Technical Details

• Language Support: Rust only (where unwrap actually matters)
• Activation: Automatically activates when you open a Rust file
• Performance: Line-by-line scanning, ignores comments
• False Positives: None, unless you put .unwrap() in a string literal (don't do that)

The Cloudflare Incident (TL;DR)

1. Database permissions change caused duplicate metadata
2. Bot management config file doubled in size
3. Oversized file exceeded 200-feature memory limit
4. Rust proxy panicked on unwrap()
5. HTTP 5xx errors across the network
6. 6 hours to full recovery

Read the full post-mortem: 18 November 2025 Outage

Philosophy

Rust's type system gives you Result and Option for a reason. unwrap() is appropriate for prototypes, examples, and tests. In production code, it's a deferred panic waiting for Murphy's Law to kick in.

This extension won't make you a better programmer, but it will make those unwraps harder to ignore when you're reviewing your own code at 2 AM before a deploy.

Contributing

Found a bug? Want to add support for expect() highlighting? PRs welcome.

Just remember: the goal isn't to eliminate all unwraps from existence. It's to make you think twice before using them.

License

GPL-3.0-only

Because free software should be free, and your production systems should be panic-free.

Disclaimer

This extension is satire, but the problem is real. The Cloudflare incident was a complex systems failure involving database changes, configuration management, and error handling. This extension focuses on the unwrap() aspect because it's a concrete, actionable lesson for Rust developers.

No disrespect intended to Cloudflare's engineers, who responded professionally and published a detailed post-mortem. We all write unwraps we shouldn't. This extension just makes them more visible.