fix(vite-plugin): prevent SyntaxError when SSR module ends with // comment

[kayluhb]

Summary

When module code produced by the SSR transform ends with a single-line comment (e.g. //# sourceMappingURL=... preserved by vite-plus), the closing } of the async arrow wrapper in runInlinedModule gets absorbed into the comment:

"use strict";async (...)=>{...//# sourceMappingURL=foo.js.map}
//                                                           ^ swallowed by comment

This produces an unclosed function body and throws SyntaxError: Unexpected end of input.

Fix

Insert a newline before the closing brace so it always starts a new line, safe from trailing // comments:

- const code = `"use strict";async (${Object.keys(context).join(",")})=>{${transformed}}`;
+ const code = `"use strict";async (${Object.keys(context).join(",")})=>{${transformed}\n}`;

This is backwards-compatible — the newline is harmless when there is no trailing comment.

Reproduction

Use @cloudflare/vite-plugin with vite-plus (which preserves sourceMappingURL comments in SSR-transformed output, unlike standard Vite which strips them).

Fixes #12681

---

• Tests
  • Tests included/updated
  • Automated tests not possible - manual testing has been completed as follows:
  • Additional testing not necessary because: covered by existing tests
• Public documentation
  • Cloudflare docs PR(s):
  • Documentation not necessary because: bug fix

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Latest commit: 50d2c47

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[workers-devprod]

Codeowners approval required for this PR:

• ✅ @cloudflare/wrangler

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[devin-ai-integration]

✅ Devin Review: No Issues Found

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

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[penalosa]

I'm pretty certain this is a bug in Vite plus, but this workaround seems okay

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commit: 50d2c47