jsonc formatter adds trailing commas and triggers warnings

[matthewmueller]

Check for existing issues

• Completed

Describe the bug / provide steps to reproduce it

Create a jsonc file like, e.g. config.jsonc

// This is a dot schema file. It defines the server configuration for your project.
// For more information, visit https://dot.io/docs/schema
{
  // Application name
  "name": "", // e.g., "my-app"
  // Domains for the app (leave empty for local development)
  // Example: ["example.com", "api.example.com"]
  "domains": [],
  // Host servers to deploy to
  "hosts": {
    "main": {
      "host": "localhost:2222",
      "admin": "ubuntu",
      "user": "dot"
    }
  },
}

Then hit save, the formatter will append trailing commas, leading to warnings.

Environment

Zed: v0.162.5 (Zed)
OS: macOS 14.6.1
Memory: 64 GiB
Architecture: aarch64

If applicable, add mockups / screenshots to help explain present your vision of the feature

Quick video:

CleanShot.2024-11-28.at.14.56.37.mp4

I'd expect the formatter to not generate trailing commas. This also matches what VSCode does.

If applicable, attach your Zed.log file to this issue.

Zed.log

[notpeter]

This is an upstream prettier issue:

• Prettier should *not* format JSONC with trailing commas prettier/prettier#15956

Duplicate of:

• JSONC Self-Corruption #17487

Explicitly called out in the Zed JSON Language Docs.