Improve type error ranges in computed collections

[kerams]

Fixes #15361, fixes #7670.

Before and after

[baronfel]

Why does f2 error on the string, but f3 errors on the int list? Naively I expect the first element to 'fix' the element type of the seq CE. EDIT: I cannot read, let this sit here as monument to my lack of literacy.

[kerams]

f2 has a type annotation. The type hints make it harder to spot.

[kerams]

On an unrelated note, not sure if this is an inherent limitation of implicit yields or just an oversight:

> let y = [ yield 1L; if true then yield 2 ];;
val y: int64 list = [1L; 2L]

> let y = [ 1L; if true then 2 ];;

  let y = [ 1L; if true then 2 ];;
  --------^^^^^^^^^^^^^^^^^^^^^^

stdin(6,9): error FS0193: Type constraint mismatch. The type
    'int'
is not compatible with type
    'int64'

[psfinaki]

Thanks @kerams, with PRs like this it really feels like we are cutting off all the rough edges in the language and it's nearing perfection :)

[vzarytovskii]

On an unrelated note, not sure if this is an inherent limitation of implicit yields or just an oversight:

> let y = [ yield 1L; if true then yield 2 ];;
val y: int64 list = [1L; 2L]

> let y = [ 1L; if true then 2 ];;

  let y = [ 1L; if true then 2 ];;
  --------^^^^^^^^^^^^^^^^^^^^^^

stdin(6,9): error FS0193: Type constraint mismatch. The type
    'int'
is not compatible with type
    'int64'

I think it's an oversight when we were doing implicit conversions.