Fix dynamic chunk loading on wrangler pages dev for _worker.js/ directory

[GregBrimble]

Fixes #3148.

What this PR solves / how to test:

Associated docs issue(s)/PR(s):

• [insert associated docs issue(s)/PR(s)]

Author has included the following, where applicable:

• Tests
• Changeset (Changeset guidelines)

Reviewer is to perform the following, as applicable:

• Checked for inclusion of relevant tests
• Checked for inclusion of a relevant changeset
• Checked for creation of associated docs updates
• Manually pulled down the changes and spot-tested

[changeset-bot]

🦋 Changeset detected

Latest commit: 574561d

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

[github-actions]

A wrangler prerelease is available for testing. You can install this latest build in your project with:

npm install --save-dev https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/runs/4981081436/npm-package-wrangler-3175

You can reference the automatically updated head of this PR with:

npm install --save-dev https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/prs/3175/npm-package-wrangler-3175

Or you can use npx with this latest build directly:

npx https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/runs/4981081436/npm-package-wrangler-3175 dev path/to/script.js

Additional artifacts:

npm install https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/runs/4981081436/npm-package-cloudflare-pages-shared-3175

Note that these links will no longer work once the GitHub Actions artifact expires.

[codecov]

Codecov Report

Merging #3175 (742dee4) into main (7e58071) will decrease coverage by 0.03%.
The diff coverage is 56.66%.

❗ Current head 742dee4 differs from pull request most recent head 574561d. Consider uploading reports for the commit 574561d to get more accurate results

@@            Coverage Diff             @@
##             main    #3175      +/-   ##
==========================================
- Coverage   74.62%   74.59%   -0.03%     
==========================================
  Files         179      179              
  Lines       10926    11031     +105     
  Branches     2908     2934      +26     
==========================================
+ Hits         8153     8229      +76     
- Misses       2773     2802      +29     

Impacted Files	Coverage Δ
packages/wrangler/src/dev.tsx	85.18% <ø> (+0.06%)	⬆️
...ckages/wrangler/src/pages/functions/buildWorker.ts	68.53% <ø> (ø)
packages/wrangler/src/pages/dev.ts	17.33% <7.69%> (-0.81%)	⬇️
packages/wrangler/src/dev/start-server.ts	67.26% <75.00%> (-0.21%)	⬇️
packages/wrangler/src/api/dev.ts	59.34% <100.00%> (ø)
packages/wrangler/src/bundle.ts	93.64% <100.00%> (+0.25%)	⬆️
packages/wrangler/src/traverse-module-graph.ts	100.00% <100.00%> (ø)

... and 22 files with indirect coverage changes

[petebacondarwin]

Is it possible that additionalModules and moduleCollector.modules contain duplicates?
Do we care? Probably not here, since all we are doing is writing them out to the directory containing the entry-point, so we just waste some time writing files more than once.

But this modules array is returned and could that result in multiple copies of the same file being added to an HTTP Form?

[GregBrimble]

HTTP form defaults automatically de-dupes by preferring the last entry. Workerd crashed. I added this commit to more gracefully handle the unlikely case of a collision: 742dee4

[petebacondarwin]

There is a test! It was previously erroneously passing.
So despite there being annotations about code coverage this is actually checked by that test.

We do need a changeset though!

[dario-piotrowicz]

is this missing a changeset?

Pete already asked for it, sorry I missed that 🙈