add-interactive: reject malformed numerical input

The list-and-choose interface accepts malformed input such as "2m3" and
interprets it as "2-", silently selecting a range to the end. This is
misleading and makes it easy to select unintended items.

Reject such input by treating it as invalid.

Signed-off-by: Seonghyeon Cho <seonghyeoncho96@gmail.com>

Author: sh-cho

add-interactive.c

@@ -396,6 +396,8 @@ static ssize_t list_and_choose(struct add_i_state *s,
 					if (endp != p + sep)
 						from = -1;
 				}
+				else
+					from = -1;
 			}
 
 			if (p[sep])