📝 Format fails on parsing a catch clause with an union type even with formatWithErrors is set to true

[ahmedelgabri]

Environment information

CLI:
  Version:                      1.9.4
  Color support:                true

Platform:
  CPU Architecture:             aarch64
  OS:                           macos

Environment:
  BIOME_LOG_PATH:               unset
  BIOME_LOG_PREFIX_NAME:        unset
  BIOME_CONFIG_PATH:            unset
  NO_COLOR:                     unset
  TERM:                         "xterm-ghostty"
  JS_RUNTIME_VERSION:           "v22.12.0"
  JS_RUNTIME_NAME:              "node"
  NODE_PACKAGE_MANAGER:         "yarn/4.1.0"

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

Formatter:
  Format with errors:           true
  Indent style:                 Tab
  Indent width:                 2
  Line ending:                  Lf
  Line width:                   120
  Attribute position:           Auto
  Bracket spacing:              BracketSpacing(false)
  Ignore:                       []
  Include:                      []

JavaScript Formatter:
  Enabled:                      true
  JSX quote style:              Single
  Quote properties:             AsNeeded
  Trailing commas:              Es5
  Semicolons:                   AsNeeded
  Arrow parentheses:            AsNeeded
  Bracket spacing:              unset
  Bracket same line:            false
  Quote style:                  Single
  Indent style:                 unset
  Indent width:                 unset
  Line ending:                  unset
  Line width:                   unset
  Attribute position:           unset

JSON Formatter:
  Enabled:                      true
  Indent style:                 unset
  Indent width:                 unset
  Line ending:                  unset
  Line width:                   unset
  Trailing Commas:              unset

CSS Formatter:
  Enabled:                      true
  Indent style:                 unset
  Indent width:                 unset
  Line ending:                  unset
  Line width:                   unset
  Quote style:                  Double

GraphQL Formatter:
  Enabled:                      true
  Indent style:                 unset
  Indent width:                 unset
  Line ending:                  unset
  Line width:                   unset
  Bracket spacing:              unset
  Quote style:                  unset

Workspace:
  Open Documents:               0

Configuration

It doesn't matter, I can reproduce it with the default config on the playground.

try {
  thing()
} catch(e: Error | MyError) { //<-- fails on this line
  
}

Playground link

https://biomejs.dev/playground/?code=dAByAHkAIAB7AAoAIAAgAHQAaABpAG4AZwAoACkACgB9ACAAYwBhAHQAYwBoACgAZQA6ACAARQByAHIAbwByACAAfAAgAE0AeQBFAHIAcgBvAHIAKQAgAHsACgAgACAACgB9AAoAIAAgAA%3D%3D

Code of Conduct

• I agree to follow Biome's Code of Conduct

[ematipico]

The playground shows an exact match with Prettier. It's not a bug. Did you miss something in the playground?

[ahmedelgabri]

Prettier works fine on the same code. https://prettier.io/playground/#N4Igxg9gdgLgprEAuEMBOBPABMAOlLLGACwEsoBzACgEp8BfLMAQxjGKriSwFE00IaLAB8sAWQx8BaGjiwB6eQB4AtCqwAzZqQA2AZyzQiZAzvJx8hBiAA0ICAAcYpaHuShm-CAHcACp4Q3FGYdb2YMNzsAIzRmMABrOBgAZWYAWzgAGXNkLX04OwgogCs4MBgAdViHZBAHNDg9ODQANzhbEBi4xJSHOPIKZHQAVwKQJrTSIbRRuzgADwdm0gzYEIB5JdiYQV8IPVJnaFqEABMOha2VhBgQgBVmqE9SRtyQprsDyh04AEVhiDwN75OzFPTzZIDH7-QHtJB5D4gACOAPgvgEDiCIGYehUUDgcFOhI66G0ZkoAGEIGk0sxaiEdB0vhQfgBBGDoUhRYZo5rZfHAxHEGBpHQVMjwPR9MBwZKBQ6kFqHDC1MB6SIgFqjACSUCJsGSYDQpCcrL1yRgGB+grG9X2cCqzBqKHqjWabQ65CaaBg6OYFFpNrsfTQ3tqlqWeiNJpgHXq5EqpFOJGQAA4AAx2Boo0gNP0Bunw95jW5RCpJlNIABMdmGTTuzCiQQRYzgaSihKJp0yzEow39cAAYoJaRyBvSeRAQPR6EA

[ematipico]

The code shared in our playground and prettier's playground are different, so my question stands. What's the bug? What's the expected result?

[ahmedelgabri]

@ematipico what do you mean by the code is different? This is the code snippet. Biome fails to parse this and errors out, prettier handles this totally fine.

try {
  thing()
} catch(e: Error | MyError) {
  
}

[ahmedelgabri]

Here is a screenshot of both playgrounds side-by-side

And the CLI

[ahmedelgabri]

Ok… I think I understand now. The failure of parsing didn't affect formatting, this is so confusing. I expect that if I'm running biome format on something and biome successfully formats it I don't see any errors. The command also returns with a zero exit code.

[ematipico]

Thank you, that provides more information. The bug isn't formatting but parsing. :)