allow specifying only "index" without extension or nothing at all to launch "wrangler dev"

[jgentes]

While using wrangler dev ./index I get

TypeError: Cannot read properties of undefined (reading '0')
    at null.build (/home/jgentes/workers/wrangler2/packages/wrangler/src/dev.tsx:411:15)

This is caused due to the entry value being verbatim what was used as a command line argument, ie. ./index, whereas the entryPoint value in result.metafile.outputs has the extension added to the file, ie ./index.js.

I'm going to submit a PR that uses what esBuild recognizes as the input value in result.metafile.inputs instead of the entry value:

const chunks = Object.entries(result.metafile.outputs).find(
        ([_path, { entryPoint }]) =>
          entryPoint === Object.keys(result.metafile.inputs)[0]
      ) // assumedly only one entry point

[changeset-bot]

🦋 Changeset detected

Latest commit: fc2ad31

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
wrangler	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[JacobMGEvans]

Looks good to me, looking forward to the bonus wrangler dev using default entrypoint

[threepointone]

• Could you add a changeset please? Run npx changeset in the root of the project, and add the title of this PR as a patch to wrangler.
• Could you also add this logic to wrangler publish? Here - https://github.com/cloudflare/wrangler2/blob/19d3833433be55ede84740b0f99a951c608e0a23/packages/wrangler/src/publish.ts#L128

[threepointone]

LGTM!