Next.js Debugger + Sentry Issue Reproduction

This repository demonstrates an issue where breakpoints don't work when Sentry is enabled using withSentryConfig.

Setup

1. Clone this repository
2. Install dependencies:

   yarn install

Issue Description

When using Sentry's withSentryConfig in next.config.mjs, breakpoints set in both the middleware (src/middleware.ts) and API routes don't work. This can be demonstrated using two different launch configurations.

How to Test

Test Case 1: Without Sentry (Breakpoints Work)

1. In VS Code, select the "WITHOUT SENTRY: debug server-side" configuration
2. Start debugging (F5)
3. Set breakpoints in:
   • src/middleware.ts at the line with console.log("Add a breakpoint here")
   • src/app/api/test/route.ts at the lines with console.log("Add a breakpoint here")
4. Visit http://localhost:3000 and click either the "Test GET Request" or "Test POST Request" button
5. Observe that all breakpoints are hit and debugging works as expected

Test Case 2: With Sentry (Breakpoints Do Not Work)

1. In VS Code, select the "WITH SENTRY: debug server-side" configuration
2. Start debugging (F5)
3. Set breakpoints in:
   • src/middleware.ts at the line with console.log("Add a breakpoint here")
   • src/app/api/test/route.ts at the lines with console.log("Add a breakpoint here")
4. Visit http://localhost:3000 and click either the "Test GET Request" or "Test POST Request" button
5. Observe that none of the breakpoints are hit (although the console.log outputs appear in the terminal)

VS Code Launch Configuration

The repository includes the following launch configuration in .vscode/launch.json:

{
  "version": "0.2.0",
  "configurations": [
    {
      "name": "WITH SENTRY: debug server-side",
      "type": "node-terminal",
      "request": "launch",
      "command": "yarn dev",
      "env": {
        "WITH_SENTRY": "true"
      }
    },
    {
      "name": "WITHOUT SENTRY: debug server-side",
      "type": "node-terminal",
      "request": "launch",
      "command": "yarn dev",
      "env": {
        "WITH_SENTRY": "false"
      }
    }
  ]
}

Environment Details

• Next.js version: 15.4.1
• @sentry/nextjs version: 9.40.0
• Node.js version: v22.14.0
• Operating System: macOS 15.5

Additional Notes

• The middleware contains a simple request ID generator and logger
• Console.log statements have been added at the locations where breakpoints should work
• The issue affects both middleware & route debugging when WithSentryConfig is enabled