🐛 `npx @biomejs/biome migrate` command crashes

[bnjox]

Environment information

CLI:
  Version:                      1.8.1
  Color support:                true

Platform:
  CPU Architecture:             x86_64
  OS:                           linux

Environment:
  BIOME_LOG_DIR:                unset
  NO_COLOR:                     unset
  TERM:                         "xterm-256color"
  JS_RUNTIME_VERSION:           "v20.14.0"
  JS_RUNTIME_NAME:              "node"
  NODE_PACKAGE_MANAGER:         "npm/10.7.0"

Biome Configuration:
  Status:                       Loaded successfully
  Formatter disabled:           false
  Linter disabled:              false
  Organize imports disabled:    false
  VCS disabled:                 true

Workspace:
  Open Documents:               0

What happened?

npx @biomejs/biome migrate

Biome encountered an unexpected error                                                                                                                                  
This is a bug in Biome, not an error in your code, and we would appreciate it if you could report it to https://github.com/biomejs/biome/issues/ along with the following information to help us fixing the issue:
                                                                         
Source Location: /home/runner/work/biome/biome/crates/biome_rowan/src/ast/mod.rs:686:41 
Thread Name: main                                             
Message: Malformed list, node expected but found token COMMA@1621..1622 "," [] [] instead. You must add missing markers for missing elements.

Expected result

It should update the biome.json file or something positive on what next to do, but not an error or bug report like this.

Code of Conduct

• I agree to follow Biome's Code of Conduct

[ematipico]

Is it possible that you have a leading comma in biome.json and that you enabled it in the configuration file? e.g.

{
	"json": { "parser": { "allowTrailingCommas": true } }
}

[bnjox]

I have it in the javascript.formatter property section, and it is "trailingCommas": "es5"

[ematipico]

Could you share your biome.json file? Or a reproduction. Without more information we can't understand where the issue comes from

[bnjox]

{
  "$schema": "https://biomejs.dev/schemas/1.8.1/schema.json",
  "formatter": {
    "enabled": true,
    "formatWithErrors": false,
    "indentStyle": "space",
    "lineEnding": "lf",
    "lineWidth": 100,
    "ignore": [
      "node_modules",
      ".svelte-kit",
      ".husky",
      "**/.DS_Store",
      "**/node_modules",
      "./build",
      "./.svelte-kit",
      "./package",
      "**/.env",
      "**/.env.*",
      "**/*.db",
      "**/pnpm-lock.yaml",
      "**/package-lock.json",
      "**/yarn.lock"
    ]
  },
  "organizeImports": { "enabled": true },
  "linter": {
    "rules": {
      "recommended": true,
      "a11y": { "recommended": true },
      "complexity": {
        "recommended": true,
        "noUselessTernary": "error",
        "noVoid": "warn",
        "useSimplifiedLogicExpression": "warn"
      },
      "correctness": {
        "recommended": true,
        "noNewSymbol": "warn",
        "noUndeclaredVariables": "warn",
        "noUnusedImports": "warn",
        "noUnusedVariables": "warn",
        "useHookAtTopLevel": "error"
      },
      "nursery": {
        "recommended": true,
        "noDuplicateElseIf": "warn",
        "noDuplicateJsonKeys": "error",
        "useImportRestrictions": "warn",
        "useSortedClasses": {
          "level": "warn",
          "options": { "attributes": ["class"] }
        }
      },
      "performance": { "recommended": true },
      "security": { "recommended": true },
      "style": {
        "recommended": true,
        "noImplicitBoolean": "error",
        "noNegationElse": "warn",
        "noShoutyConstants": "error",
        "useBlockStatements": "error",
        "useCollapsedElseIf": "warn",
        "useForOf": "warn",
        "useFragmentSyntax": "warn",
        "useShorthandAssign": "warn",
        "useSingleCaseStatement": "error"
      },
      "suspicious": {
        "recommended": true,
        "noApproximativeNumericConstant": "error",
        "noConsoleLog": "warn",
        "noEmptyBlockStatements": "warn",
        "noMisrefactoredShorthandAssign": "error",
        "useAwait": "warn"
      }
    },
    "ignore": ["node_modules", ".svelte-kit", ".husky"]
  },
  "javascript": {
    "formatter": {
      "jsxQuoteStyle": "double",
      "quoteProperties": "asNeeded",
      "trailingCommas": "es5",
      "semicolons": "asNeeded",
      "arrowParentheses": "always",
      "bracketSpacing": true,
      "bracketSameLine": false,
      "quoteStyle": "double",
      "attributePosition": "auto"
    }
  },
  "overrides": [{ "include": ["*.svelte"] }]
}

This is the biome.json and this is the repo

[Sec-ant]

I can reproduce from your repo. I narrowed it down and found it was triggered by the promotion of the once nursery rule useImportRestrictions when it is not the last rule in the nursery group. In your example it is followed by useSortedClasses. When I put it as the last rule of that group, or delete it from the group, the migration command succeeds.

This might be caused by the left over comma when a promoted rule was deleted from that object:

{
-  "ruleA": "error",
+  ,
   "ruleB": "error"
}