Before:
  runtime ale_linters/cairo/sierra.vim

After:
  call ale#linter#Reset()

Execute(The starknet handler should handle error messages correctly):
  AssertEqual
  \ [
  \   {
  \     'lnum': 16,
  \     'col': 25,
  \     'text': 'Plugin diagnostic: Type not found',
  \     'type': 'E',
  \   },
  \ ],
  \ ale_linters#cairo#sierra#Handle(bufnr(''), [
  \   'error: Plugin diagnostic: Type not found',
  \   '  --> lib.cairo:16:25',
  \ ])