Koa instrumentation does not work with the New Relic ESM module loader

[markdb314]

Description

When attempting to load the New Relic Agent (v9.7.3) using the ESM module loader described here, the automatic instrumentation for Koa fails with the following error:

{"v":0,"level":40,"name":"newrelic","hostname":"0bfcea2519cb","pid":82743,"time":"2022-12-14T21:10:08.234Z","msg":"Custom instrumentation for koa failed. Please report this to the maintainers of the custom instrumentation.","component":"shimmer","stack":"TypeError: Cannot convert undefined or null to object\n at Function.keys (<anonymous>)\n at Object.initialize [as onRequire] (/my-system/node_modules/@newrelic/koa/lib/instrumentation.js:10:31)\n at instrumentPostLoad (/my-system/node_modules/newrelic/lib/shimmer.js:534:25)\n at _postLoad (/my-system/node_modules/newrelic/lib/shimmer.js:591:12)\n at Object.instrumentPostLoad (/my-system/node_modules/newrelic/lib/shimmer.js:477:20)\n at wrapModule (file:///my-system/node_modules/newrelic/lib/esm-shim.mjs:35:18)\n at file:///my-system/node_modules/koa/dist/koa.mjs?hasNrInstrumentation=true:4:28\n at ModuleJob.run (node:internal/modules/esm/module_job:193:25)\n at async Promise.all (index 0)\n at async ESMLoader.import (node:internal/modules/esm/loader:526:24)","message":"Cannot convert undefined or null to object"}

The root cause is at line 10 of instrumentation.js
if (!shim || !Koa || Object.keys(Koa.prototype).length > 1) {

When loaded via the ESM module loader, `Koa.prototype' is undefined.

I was able to fix it by simply adding the following line before the if statement above:
Koa.prototype = Koa.default.prototype;

The 'Koa.default' export was added for this purpose in the Koa project. See:

• MJS build has different shape than non-MJS build koajs/koa#1513
• miwnwski/koa@4f78703

Steps to Reproduce

Run the New Relic agent in a Koa project following the instructions for using the ESM module loader, and look at the agent logs to find the error above.

[workato-integration]

https://issues.newrelic.com/browse/NEWRELIC-5896

[jmartin4563]

Hiya @markdb314! Thank you for the (awesomely) detailed bug report, I'll be taking a look at this and will reach out if I have any questions :)

[jmartin4563]

Hi again @markdb314, v7.1.1 has been released with a fix for this, give it a spin and let me know how it works for you!

[markdb314]

Works great, thanks for the speedy fix! 👏👏👏