Broken production with Metro bundler (ReferenceError)

Hi 👋

On the latest version, a modification (somewhere around here) broke the metro bundler in production mode (and possibly other production apps? It’s not tied to minification, but I didn’t tried on other bundlers).

urql version: 1.9.7

Steps to reproduce

1. Create a new React Native project
2. Add urql@1.9.7, wrap your app in a Provider with an urql client
3. Build your app for production
4. Starts your app. It will crash at client init.

Expected behavior

No JS ReferenceError.

Actual behavior

For some reason, the variable is not declared.

Debugging

In order to spot the issue, I created a server to serve the unminified production bundle to my debug application. Create a file at project root:

// server.js

const express = require("express");
const app = express();

app.use((req, res, next) => {
  console.log(req.url);
  res.setHeader("Content-Type", "application/javascript");
  next();
});

app.use("/", express.static("."));
app.use("/assets", express.static("."));
app.get("/status", (_req, res) => {
  res.send("packager-status:running");
});

app.listen(8081, () => {
  console.log("Serving directory as localhost:8081");
});

Build a bundle with:

yarn react-native bundle --entry-file index.js --bundle-output index.bundle --platform ios --dev false --minify false

Then run the server.js file to fake metro bundler, it will be easier to debug.

Fix

The missing declaration is f:

If I add it manually to the bundle, it works:

[zoontek]

Thanks, that was fast!

[kitten]

This should be released in @urql/core@1.11.5, so a quick yarn upgrade @urql/core should fix the issue 👍 https://github.com/FormidableLabs/urql/releases/tag/%40urql%2Fcore%401.11.5