Expo Router projects fail in Bolt: 500 error + MIME type ('application/json') not executable

[bbytetech]

Description

When creating or running an Expo Router project inside Bolt (stackblitz/bolt.new), the build consistently fails on expo-router/entry.bundle with a MIME type and 500 error.

Error shown in the console:

Refused to execute script from ‘…/expo-router/entry.bundle?platform=web&…’
because its MIME type (‘application/json’) is not executable,
and strict MIME type checking is enabled.

500 (Internal Server Error)

This makes Expo 53/54 projects with expo-router unusable in Bolt.

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Steps to Reproduce

1. Create a new Bolt project with Expo + Expo Router (latest Expo SDK 53 or 54).
2. Run the dev server.
3. Open the web preview.
4. Observe the error in console.

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Expected Behavior

Expo Router entry bundle should load properly in the browser, with no MIME type mismatch.

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Actual Behavior

Preview fails with 500 + MIME error.
Mobile preview also fails to load.

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Environment

• Bolt (stackblitz/bolt.new)
• Expo SDK: 53 and 54
• Expo Router: 2.x / 3.x
• React Native: latest
• Browser: Chrome (latest, macOS)

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Additional Info

• Using the same project locally with Expo CLI (npx expo start) works fine.
• Only fails in Bolt’s preview container.
• Screenshots attached.