Fix handle_down error message (#2)

* Fix handle_down error message

It was printing a tuple with `~s`, and also tried to pretty print a fat
call stack more than a hundred columns into the first line, which put
together made for some confusing exception-during-error-handling
messages in the erlang console.

* Switch to unicode formatting in handle_down

bindings/erlang/src/vanillae_man.erl

@@ -189,9 +189,11 @@ handle_down(PID, Mon, Info, State = #s{fetchers = Fetchers}) ->
         {value, #fetcher{time = Time, node = Node, from = From, req = R}, Remaining} ->
             TS = calendar:system_time_to_rfc3339(Time, [{unit, nanosecond}]),
             Format =
-                "ERROR ~s: Fetcher process ~p making request to ~p exited with ~p~n"
-                "Request contents:~n~n"
-                "~s",
+                "ERROR ~ts: Fetcher process ~130tp exited while making request to ~130tp~n"
+                "Exit reason:~n"
+                "~tp~n"
+                "Request contents:~n"
+                "~tp~n~n",
             Formatted = io_lib:format(Format, [TS, PID, Node, Info, R]),
             Message = unicode:characters_to_list(Formatted),
             ok = gen_server:reply(From, {error, Message}),