Improve json decode error messages

When printing errors include the position that the error occured at
if included in the error.

Author: dgud

lib/stdlib/src/erl_stdlib_errors.erl

@@ -47,6 +47,8 @@ format_error(_Reason, [{M,F,As,Info}|_]) ->
                   format_unicode_error(F, As);
               io ->
                   format_io_error(F, As, Cause);
+              json ->
+                  format_json_error(F, As, Cause);
               _ ->
                   []
           end,
@@ -633,6 +635,11 @@ check_io_arguments([Type|TypeT], [Arg|ArgT], No) ->
              check_io_arguments(TypeT, ArgT, No+1)]
     end.
 
+format_json_error(_F, _As, #{position := Position}) ->
+    [{general, io_lib:format("Occured at position ~w", [Position])}];
+format_json_error(_, _, _) ->
+    [""].
+
 format_ets_error(delete_object, Args, Cause) ->
     format_object(Args, Cause);
 format_ets_error(give_away, [_Tab,Pid,_Gift]=Args, Cause) ->

lib/stdlib/src/json.erl

@@ -541,7 +541,8 @@ invalid_byte(Bin, Skip) ->
     error({invalid_byte, Byte}, none, error_info(Skip)).
 
 error_info(Skip) ->
-    [{error_info, #{cause => #{position => Skip}}}].
+    [{error_info, #{cause => #{position => Skip},
+                    module => erl_stdlib_errors}}].
 
 %%
 %% Format implementation