[Bug]: Unexpected non-whitespace character error when building @rsdoctor/rspack-plugin v1.1.1

[giavinh79]

Version

System:
    OS: macOS 15.5
    CPU: (10) arm64 Apple M1 Pro
    Memory: 100.14 MB / 32.00 GB
    Shell: 5.9 - /opt/homebrew/bin/zsh
Browsers:
    Chrome: 137.0.7151.120
    Edge: 137.0.3296.93
    Safari: 18.5
npmPackages:
    @rsdoctor/rspack-plugin: 1.1.0 => 1.1.0
Binaries:
    Node: 20.15.1 - ~/.nvm/versions/node/v20.15.1/bin/node
    pnpm: 8.14.0 - ~/.nvm/versions/node/v20.15.1/bin/pnpm

Details

In my Rspack config, I have configured Rsdoctor in the plugins field as something like this:

import { RsdoctorRspackPlugin } from '@rsdoctor/rspack-plugin';

...

{
  ...
  plugins: [
     ....,
    process.env.RSDOCTOR && new RsdoctorRspackPlugin()
  ]
}

On version 1.1.0 of @rsdoctor/rspack-plugin, when running a Rspack build, Rsdoctor works as expected (opens a UI with bundle analysis). However when changing it to v1.1.1 (or latest, 1.1.4), I encounter this error in the terminal on trying to build:

/Users/user/project/node_modules/.pnpm/@rsdoctor+utils@1.1.1_@rspack+core@1.3.15_@swc+helpers@0.5.17__webpack@5.94.0_@swc+core_cbc4660d53021a296d716d034470cb0c/node_modules/@rsdoctor/utils/dist/cjs/common/global-config.js:71
    mcpJson = JSON.parse(import_fs.default.readFileSync(mcpPortFilePath, "utf8"));
                   ^
SyntaxError: Unexpected non-whitespace character after JSON at position 73
    at JSON.parse (<anonymous>)
    at Object.writeMcpPort (/Users/user/project/node_modules/.pnpm/@rsdoctor+utils@1.1.1_@rspack+core@1.3.15_@swc+helpers@0.5.17__webpack@5.94.0_@swc+core_cbc4660d53021a296d716d034470cb0c/node_modules/@rsdoctor/utils/dist/cjs/common/global-config.js:71:20)
    at RsdoctorServer.bootstrap (/Users/user/project/node_modules/.pnpm/@rsdoctor+sdk@1.1.1_@rspack+core@1.3.15_@swc+helpers@0.5.17__webpack@5.94.0_@swc+core@1_ae512a4388d0ed3c95be1642c2f22d7f/node_modules/@rsdoctor/sdk/dist/cjs/sdk/server/index.js:115:32)
    at processTicksAndRejections (node:internal/process/task_queues:95:5)
    at async RsdoctorSDK.bootstrap (/Users/user/project/node_modules/.pnpm/@rsdoctor+sdk@1.1.1_@rspack+core@1.3.15_@swc+helpers@0.5.17__webpack@5.94.0_@swc+core@1_ae512a4388d0ed3c95be1642c2f22d7f/node_modules/@rsdoctor/sdk/dist/cjs/sdk/sdk/index.js:73:20)
Warning: command "rspack --env stage=staging" exited with non-zero status code

Reproduce link

https://github.com/giavinh79/rsdoctor-build-error

Reproduce Steps

The reproduction example linked above isn't identical to my project, but the error is still quite similar when built and run in my environment.

So in the reproduction link above:

1. pnpm i
2. pnpm run build
3. I get back the error:

> @examples/rsdoctor-rspack-cra-ts@0.1.1 build /Users/giavinh.lam/dev/projects/rspack-minimal
> npm run build:s && npm run build:m


> @examples/rsdoctor-rspack-cra-ts@0.1.1 build:s
> ENABLE_CLIENT_SERVER=false NODE_ENV=production rspack build -c ./rspack.config.js

undefined:7
}
^

SyntaxError: Unexpected non-whitespace character after JSON at position 73
    at JSON.parse (<anonymous>)
    at Object.writeMcpPort (/Users/giavinh.lam/dev/projects/rspack-minimal/node_modules/.pnpm/@rsdoctor+utils@1.1.1_@rspack+core@1.4.0-beta.1_webpack@5.99.9/node_modules/@rsdoctor/utils/dist/cjs/common/global-config.js:71:20)
    at RsdoctorServer.bootstrap (/Users/giavinh.lam/dev/projects/rspack-minimal/node_modules/.pnpm/@rsdoctor+sdk@1.1.1_@rspack+core@1.4.0-beta.1_webpack@5.99.9/node_modules/@rsdoctor/sdk/dist/cjs/sdk/server/index.js:115:32)
    at process.processTicksAndRejections (node:internal/process/task_queues:95:5)
    at async RsdoctorSDK.bootstrap (/Users/giavinh.lam/dev/projects/rspack-minimal/node_modules/.pnpm/@rsdoctor+sdk@1.1.1_@rspack+core@1.4.0-beta.1_webpack@5.99.9/node_modules/@rsdoctor/sdk/dist/cjs/sdk/sdk/index.js:73:20)

4. If I change the version back to 1.1.0, the build runs fine.

[easy1090]

Got this, we will check this error.

[easy1090]

I use your repository locally, the rsdoctor version of 1.1.1, and I can't reproduce this problem.

pnpm: 10
node: 22.15.1
rsdoctor: 1.1.1

[giavinh79]

I tested with your node.js and pnpm version and was unable to get it working. However, I ended up removing this file ~/.cache/rsdoctor/mcp.json and restarted, and things seem to be working now as expected.

[easy1090]

I'll try to catch this error and investigate why the parsing failed. #1147

[7rulnik]

I faced it too using v1.1.5 in CI

SyntaxError: Unexpected end of JSON input
    at JSON.parse (<anonymous>)
    at Object.writeMcpPort (/home/jenkins/agent/workspace/selene/node_modules/@rsdoctor/utils/dist/cjs/common/global-config.js:50:20)
    at RsdoctorServer.bootstrap (/home/jenkins/agent/workspace/selene/node_modules/@rsdoctor/sdk/dist/cjs/sdk/server/index.js:115:32)
    at process.processTicksAndRejections (node:internal/process/task_queues:105:5)
    at async RsdoctorSDK.bootstrap (/home/jenkins/agent/workspace/selene/node_modules/@rsdoctor/sdk/dist/cjs/sdk/sdk/index.js:[7]

But could not reproduce it on purpose

[easy1090]

I faced it too using v1.1.5 in CI

SyntaxError: Unexpected end of JSON input
    at JSON.parse (<anonymous>)
    at Object.writeMcpPort (/home/jenkins/agent/workspace/selene/node_modules/@rsdoctor/utils/dist/cjs/common/global-config.js:50:20)
    at RsdoctorServer.bootstrap (/home/jenkins/agent/workspace/selene/node_modules/@rsdoctor/sdk/dist/cjs/sdk/server/index.js:115:32)
    at process.processTicksAndRejections (node:internal/process/task_queues:105:5)
    at async RsdoctorSDK.bootstrap (/home/jenkins/agent/workspace/selene/node_modules/@rsdoctor/sdk/dist/cjs/sdk/sdk/index.js:[7]

But could not reproduce it on purpose

@7rulnik this issue has been fixed on 1.1.6, you can try this again. ❤️