Don't check for length

This was necessary for the indexing operation but Astring can take care
of it itself.

Author: Leonidas-from-XIV

lib/block.ml

@@ -217,9 +217,7 @@ let guess_ocaml_kind contents =
 
 let ends_by_semi_semi c =
   match List.rev c with
-  | h :: _ ->
-      let len = String.length h in
-      len > 2 && Astring.String.is_suffix ~affix:";;" h
+  | h :: _ -> Astring.String.is_suffix ~affix:";;" h
   | _ -> false
 
 let pp_line_directive ppf (file, line) = Fmt.pf ppf "#%d %S" line file