[vite-plugin-cloudflare] Surface export type fetch errors

[xgame92]

Fixes #15370.

When Miniflare returned a non-success response while the Vite plugin fetched Worker export types, the plugin attempted to parse the plain-text error body as JSON. This replaced the underlying failure with an unrelated SyntaxError.

This change checks the response status before JSON parsing and reports the Worker name, HTTP status, and original response body. Successful JSON responses keep their existing behavior.

---

• Tests
  • Tests included/updated
  • Automated tests not possible - manual testing has been completed as follows:
  • Additional testing not necessary because:
• Public documentation
  • Cloudflare docs PR(s):
  • Documentation not necessary because: this only improves an internal development error message and adds regression coverage.

Local verification:

• pnpm test (199 tests)
• pnpm check:type
• type-aware Oxlint on changed TypeScript files
• Oxfmt check on all changed files
• pnpm build

---

[changeset-bot]

🦋 Changeset detected

Latest commit: 9b67e0c

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

This PR includes changesets to release 1 package

Name	Type
@cloudflare/vite-plugin	Patch

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[workers-devprod]

Codeowners approval required for this PR:

• @cloudflare/wrangler

Show detailed file reviewers

• .changeset/calm-rivers-report.md: [@cloudflare/wrangler]
• packages/vite-plugin-cloudflare/src/tests/cloudflare-environment.spec.ts: [@cloudflare/wrangler]
• packages/vite-plugin-cloudflare/src/cloudflare-environment.ts: [@cloudflare/wrangler]

[devin-ai-integration]

✅ Devin Review: No Issues Found

Devin Review analyzed this PR and found no bugs or issues to report.

[pkg-pr-new]

@cloudflare/autoconfig

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@cloudflare/build-output-utils

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@cloudflare/codemods

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@cloudflare/config

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create-cloudflare

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@cloudflare/deploy-helpers

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@cloudflare/kv-asset-handler

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miniflare

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@cloudflare/pages-functions

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@cloudflare/pages-shared

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@cloudflare/unenv-preset

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@cloudflare/vite-plugin

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@cloudflare/vitest-plugin

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@cloudflare/workers-auth

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@cloudflare/workers-editor-shared

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@cloudflare/workers-utils

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wrangler

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commit: 9b67e0c