🐛 bug report

I’m getting inconsistent build behavior. I get errors every time. But if I start making modifications to files, sometimes the build will succeed. Once it succeeds once, subsequent builds succeed. However, when debugging in Chrome, the debugger’s position is out of sync with the file contents (I can tell that it’s executing a different line than the UI indicates).

Once I get a successful build, I can quit and then attempt the build again and it will succeed, albeit with the above oddities. Clearing the output folder and cache takes me back to a non-buildable state (with the same source files).

I really hate bringing this to your team without a reproducible sample in-hand, but I’ve been searching and working on this issue for hours now and haven’t made any meaningful progress towards understanding the issue or narrowing it down. I intend to ask some other engineers to build it in the morning to try to narrow it down further—maybe it’s an environmental issue, though it seems somewhat unlikely.

🎛 Configuration (.babelrc, package.json, cli command)

Running yarn parcel test-index.html

//tsconfig.json
{
    "compilerOptions": {
        "target": "es5",
        "module": "commonjs",
        "outDir": "out",
        "sourceMap": true
    }
}

//.parcelrc
{
  "extends": "@parcel/config-default",
  "transformers": {
    "*.{ts,tsx}": ["@parcel/transformer-typescript-tsc"]
  }
}

🤔 Expected Behavior

Expected it to build/launch.

😯 Current Behavior

I’m getting the following error…

Server running at http://localhost:1234
⠼ Bundling...
node:internal/streams/buffer_list:97
    return this.head.data;
                     ^

TypeError: Cannot read properties of null (reading 'data')
    at BufferList.first (node:internal/streams/buffer_list:97:22)
    at howMuchToRead (node:internal/streams/readable:385:27)
    at TapStream.Readable.read (node:internal/streams/readable:430:7)
    at flow (node:internal/streams/readable:1012:34)
    at resume_ (node:internal/streams/readable:993:3)
    at processTicksAndRejections (node:internal/process/task_queues:83:21)

The precise text before the error varies (e.g. bundling, bundling runtime, packaging test-index.html, etc.).

💁 Possible Solution

I’m at a complete loss. I’ve never experienced this with other parcel-based typescript projects.

🔦 Context

I’m working on porting and TypeScript-ifying a large JavaScript library intended for the browser. I reached a point where I felt like it was ready to put through it’s paces, but then hit this hurdle.

💻 Code Sample

I tried to pare this down to something that I could share or even narrow down the culprit. I tried deleting large hunks of code and building. Eventually I did get it to work. But then when clearing .parcel-cache and dist subsequent builds didn’t work. So there seems to be some state at play other than just “what do the files look like on disk” that I’ve been unable to pin down.

Since I can’t provide the environment, I want to at least describe the stateful behavior I’m seeing…

• Delete .parcel-cache and dist
• yarn parcel test-index.html

Server running at http://localhost:1234
⠴ Optimizing test-index.[hash].js...
node:internal/streams/buffer_list:97
    return this.head.data;
                     ^

TypeError: Cannot read properties of null (reading 'data')
    at BufferList.first (node:internal/streams/buffer_list:97:22)
    at howMuchToRead (node:internal/streams/readable:385:27)
    at TapStream.Readable.read (node:internal/streams/readable:430:7)
    at flow (node:internal/streams/readable:1012:34)
    at resume_ (node:internal/streams/readable:993:3)
    at processTicksAndRejections (node:internal/process/task_queues:83:21)
error Command failed with exit code 1.

• Comment out an entire file (even though it’s referenced elsewhere and so it creates an error in the code)
• yarn parcel test-index.html

Server running at http://localhost:1234
√ Built in 2.13s

• Uncomment that file and save it

Server running at http://localhost:1234
√ Built in 586ms

• CTRL+C
• yarn parcel test-index.html

Server running at http://localhost:1234
√ Built in 22ms

• CTRL+C
• Delete .parcel-cache and dist
• yarn parcel test-index.html

Server running at http://localhost:1234
⠼ Building runtime-6bd5baf8476e8c86.js...
node:internal/streams/buffer_list:97
    return this.head.data;
                     ^

TypeError: Cannot read properties of null (reading 'data')
    at BufferList.first (node:internal/streams/buffer_list:97:22)
    at howMuchToRead (node:internal/streams/readable:385:27)
    at TapStream.Readable.read (node:internal/streams/readable:430:7)
    at flow (node:internal/streams/readable:1012:34)
    at resume_ (node:internal/streams/readable:993:3)
    at processTicksAndRejections (node:internal/process/task_queues:83:21)
error Command failed with exit code 1.

That’s probably much more info than is truly useful…

🌍 Your Environment

Software	Version(s)
Parcel	2.0.1
Node	16.13.2
yarn	1.22.15
Operating System	Windows 10
TypeScript	4.5.4