Errors with terrible output

[xarvh]

No description provided.

[xarvh]

  listCons as fn item: item =
      fn item:
      []

Error message:

        This is a literal variant, which means its type must always be a variant type.
        
        However the annotation for `listCons`:
        
        
        says that it must have type
        
            1
        
        I need the annotation and the value to have the same type!

[xarvh]

We should make it clear that { type } should be { with type }.

This does not compile:

    selfType as TA.RawType =
        try Dict.get selfUsr env.expandedAliases as
            'nothing: bug "no self?"
            'just { type }: type

because

src/Compiler/TypeCheck.sp 949:8 

  949 |         try Dict.get selfUsr env.expandedAliases as
               ^^^
  950 |             'nothing: bug "no self?"
  951 |             'just { type }: type
  
  record attrs don't match
  $Context_LetInBody
      ["selfType"]
  
  $Why_TypeArgument
      ($USR
          ($UMR
              ($ImportsPath
                  $Core
                  ""
              )
              "src"
              "Maybe"
          )
          "Maybe"
      )
      0
      $Why_TryPattern
  
  TYPE 1 -----------------------
  { pars = core:/src/Core.List (core:/src/Core.Number), type = core:/src/Compiler/TypedAst.RawType }
  
  TYPE 2 -----------------------
  { type = 7338 }

[xarvh]

FAIL !  / TypeCheck / functions / [reg] Free tyvar should not be compatible with constructor

  listCons as fn item: item =
      fn item:
      []
  Error message:
        
        The annotation says that this variant literal should be of type:
        1
        
        However variant literals must always be of a var(iant) type.
        
        The two types are not compatible!
        [[context: $Context_LetInBody
            ["listCons"]
        ]]

Type variables are especially difficult to think about, so it might be worth to have special errors for them.

For example, in this case we could have something like:
"""
item is a free type variable, which means that, inside the function, it should be compatible with any type.
However inside the function it is used as a variant #xyz which has always type #type.
"""