Cabal provides and parses it's own configuration file. The used method 'cabal HEAD' is confused by trailing whitespaces in 'default-language' tags. The solution is to fix parsing by changing 'some anyChar' to 'munch1 isAlphaNum'. This way, only characters are parsed into a language.
[
{
"endline": 80,
"file": "Cabal-syntax/src/Language/Haskell/Extension.hs",
"function": "parsec",
"module": "Language.Haskell.Extension",
"startline": 80
}
][
{
"endline": 80,
"file": "Cabal-syntax/src/Language/Haskell/Extension.hs",
"function": "parsec",
"module": "Language.Haskell.Extension",
"startline": 80
}
]