Shifted error position for syntax errors 1 position to the left

phases/parse.ml

@@ -7,12 +7,14 @@ let get_loc lexbuf =
 let shift_loc (fname, ystart, yend, xstart, xend) yshift xshift =
     (fname, ystart + yshift, yend + yshift, xstart + xshift, xend + xshift)
 
+let shift_back lexbuf = shift_loc (get_loc lexbuf) 0 (-1)
+
 let parse_with_error lexbuf =
     try Some (Parser.program Lexer.token lexbuf) with
     | Lexer.SyntaxError msg ->
-        raise (LocError (shift_loc (get_loc lexbuf) 0 (-1), msg))
+        raise (LocError ((shift_back lexbuf), msg))
     | Parser.Error ->
-        raise (LocError (get_loc lexbuf, "syntax error"))
+        raise (LocError ((shift_back lexbuf), "syntax error"))
 
 let phase input =
     prerr_endline "- Parse input";