Version: 0.5.2

Reproduction instructions

1. Create a ruff.toml file with the contents:

   extend-select = [
       "W", # pycodestyle warnings
       "I", # isort
       "N", # pep8-naming
       "D", # pydocstyle
       "B", # flake8-bugbear
       "PYI" # flake8-pyi
   ]
   
   # Group errors by file.
   output-format = "grouped"
   
   # Show source context of error.
   show-source = true
   
   # Show summary of fixes.
   show-fixes = true

2. Create a src/foo.py file with no contents.

3. Run ruff check and see the problematic error message.

Output

❯ ruff check
ruff failed
  Cause: Failed to parse /Users/[...]/ruff.toml
  Cause: TOML parse error at line 1, column 1
  |
1 | extend-select = [
  | ^^^^^^^^^^^^^^^^^
unknown field `show-source`

The error message points to the line about extend-select when complaining about show-source as the key that is unknown. It would be better for the error to point at line 14 entirely OR, ideally, point only at show-source part of that line since that's the key in the key-value pair in the configuration file that is unknown.