🐛 BUG: `npx wrangler publish` cannot resolve root npm packages

What version of Wrangler are you using?

2.0.1

What operating system are you using?

Mac

Describe the Bug

I have an existing project was published using Wrangler 1. The wrangler.toml file looks like below.

name = "my-project-name"
main = "./"
account_id = "abc12345..."
route = "foo.bar.com/*"
workers_dev = true

[env]
compatibility_date = "2022-04-01"

[build]
command = "npm install && npm run build"

After installed wrangler2 package using npm install wrangler --save-dev and run npx wrangler publish I got the error below.

...
webpack 5.38.1 compiled successfully in 764 ms

✘ [ERROR] Could not resolve "" after running custom build: npm install && npm run build

Same project can be published without problem using wrangler1 though wrangler publish command.

Publish also works if I run npm install && npm run build directly.

[petebacondarwin]

Thanks for reporting this issue.

The problem appears to be that Wrangler 2 expects the main property to be the path to the output from the custom build.

Let’s assume that your webpack build is outputting to dist/index.js, then in wrangler.toml your would need

main = "dist/index.js"

[petebacondarwin]

One last thing. Can you tell me if you added the main field as part of your upgrade to Wrangler 2? Or was it already there from Wrangler 1? I believe that Wrangler 1 would not use this field, and that our deprecation warning ought to have told you to use dist. For example:

Delete the `build.upload.main` and `build.upload.dir` fields.
Then add the top level `main` field to your configuration file:
```
main = "dist/index.js"
```