Generate @apollo/client/invariantErrorCodes.js for each release.

[benjamn]

When an invariant fails in production, a cryptic numeric error of the form Invariant Violation: 42 is thrown, with a reference to the error codes section of invariant-packages README.md. This system was introduced in #4521 to save bundle size by stripping long error strings from production bundles, and it continues to be one of the most impactful things we've done to reduce bundle sizes.

However, this vague guidance (which was intended to suggest searching your installed node_modules/@apollo/client package for the error code) has not proven adequate in many cases, to say the least: see apollographql/invariant-packages#18, apollographql/invariant-packages#19, #6604, #5730, #5291, and #5975, to cite just a few of the many issues we've seen since #4521.

Using error codes instead of error strings remains important for production bundle sizes, but I think we can make it substantially easier to look up the error string corresponding to each error code, by generating a single file containing all the invariant error codes for each @apollo/client release.

Starting with Apollo Client 3.1.0, this manifest file can be found in @apollo/client/invariantErrorCodes.js (using an npm/yarn-installed copy of @apollo/client, since this file is generated in the ./dist directory, not checked into the repository). The file contains an explanatory comment, the @apollo/client version, and a sequential map from error numbers to the { file, node } responsible for the error.

I wish we could go back and republish old versions of @apollo/client to include this file, but at least things should be easier going forward.

[benjamn]

Here's a taste of what this file looks like:

// This file is meant to help with looking up the source of errors like
// "Invariant Violation: 35" and is automatically generated by the file
// @apollo/client/config/processInvariants.ts for each @apollo/client
// release. The numbers may change from release to release, so please
// consult the @apollo/client/invariantErrorCodes.js file specific to
// your @apollo/client version. This file is not meant to be imported.
{
  "@apollo/client version": "3.1.0",

  1: {
    file: "@apollo/client/cache/inmemory/policies.js",
    node: invariant(!old || old === which, "Cannot change root " + which + " __typename more than once")
  },

  2: {
    file: "@apollo/client/cache/inmemory/policies.js",
    node: new InvariantError("Cannot automatically merge arrays")
  },

  3: {
    file: "@apollo/client/cache/inmemory/policies.js",
    node: invariant(hasOwn.call(response, responseName), "Missing field '" + responseName + "' while computing key fields")
  },

  4: {
    file: "@apollo/client/cache/inmemory/readFromStore.js",
    node: new InvariantError("Dangling reference to missing " + objectOrReference.__ref + " object")
  },

  // ... skipping a few ...

  52: {
    file: "@apollo/client/utilities/graphql/storeUtils.js",

    node: new InvariantError("The inline argument \"" + name.value + "\" of kind \"" + value.kind + "\"" +
        'is not supported. Use variables instead of inline arguments to ' +
        'overcome this limitation.')
  },

  53: {
    file: "@apollo/client/utilities/testing/mocking/mockLink.js",
    node: invariant(queryWithoutConnection, "query is required")
  }
}

[jcreighton]

🆒 👍