Error raising

(* open Parser *)
open Location

type token =
  | EOF
  | ADD of Location.t
  | SUB of Location.t
  | MUL of Location.t
  | DIV of Location.t
  | REM of Location.t
  | LPAR of Location.t
  | RPAR of Location.t
  | INT of int * Location.t

let print_token = function
  | EOF -> print_string "EOF"
  | ADD _ -> print_string "ADD"
  | SUB _ -> print_string "SUB"
  | MUL _ -> print_string "MUL"
  | DIV _ -> print_string "DIV"
  | REM _ -> print_string "REM"
  | LPAR _ -> print_string "LPAR"
  | RPAR _ -> print_string "RPAR"
  | INT (n, _) -> print_int n

let mk_int nb pos =
  try INT (int_of_string nb, pos)
  with Failure _ -> raise (Error (Error (Printf.sprintf "Illegal integer '%s': " nb, pos)))

let newline = (['\n' '\r'] | "\r\n")
let blank = [' ' '\014' '\t' '\012']
let not_newline_char = [^ '\n' '\r']
let digit = ['0'-'9']

rule token buf =
  (* newlines *)
  | newline { Location.incr_line buf; token buf }
  (* blanks *)
  | blank + { token buf }
  (* end of file *)
  | eof { EOF }
  (* comments *)
  | "--" not_newline_char* { token buf }
  (* integers *)
  | digit+ as nb { mk_int nb (Location.mkloc (Lexing.lexeme_start_p buf) (Lexing.lexeme_end_p buf)) }
  (* commands *)
  | "+" { ADD (Location.mkloc (Lexing.lexeme_start_p buf) (Lexing.lexeme_end_p buf)) }
  | "-" { SUB (Location.mkloc (Lexing.lexeme_start_p buf) (Lexing.lexeme_end_p buf)) }
  | "*" { MUL (Location.mkloc (Lexing.lexeme_start_p buf) (Lexing.lexeme_end_p buf)) }
  | "/" { DIV (Location.mkloc (Lexing.lexeme_start_p buf) (Lexing.lexeme_end_p buf)) }
  | "%" { REM (Location.mkloc (Lexing.lexeme_start_p buf) (Lexing.lexeme_end_p buf)) }
  | "(" { LPAR (Location.mkloc (Lexing.lexeme_start_p buf) (Lexing.lexeme_end_p buf)) }
  | ")" { RPAR (Location.mkloc (Lexing.lexeme_start_p buf) (Lexing.lexeme_end_p buf)) }
  (* illegal characters *)
  | _ as c { raise (Error (Error (Printf.sprintf "Illegal character '%c': " c, Location.curr buf))) }

let rec examine_all lexbuf =
  let result =
    try token lexbuf with
    | Error err -> Location.print err; print_newline (); raise (Error err)
  in
  print_token result;
  print_string " ";
  match result with
  | EOF -> ()
  | _ -> examine_all lexbuf

let compile file =
  print_string ("File