Follow-up fix to 14655

Follow-up to rabbitmq#14655

The code to format `cacerts` and `certs_keys` needs to check if the
incoming value is a list or map, and skip it if not. This is the same
pattern as used in a later function head:

```
format_socket_opts([Head = {Name, Value} | Tail], Acc) when is_list(Value) ->
```

It ensures that the code won't be called again on an already-formatted
value.

Author: lukebakken

deps/rabbitmq_management_agent/src/rabbit_mgmt_format.erl

@@ -318,13 +318,13 @@ format_socket_opts([{user_lookup_fun, _Value} | Tail], Acc) ->
 format_socket_opts([{sni_fun, _Value} | Tail], Acc) ->
     format_socket_opts(Tail, Acc);
 %% https://www.erlang.org/doc/apps/ssl/ssl.html#t:server_option_cert/0
-format_socket_opts([{cacerts, Cacerts} | Tail], Acc) ->
+format_socket_opts([{cacerts, Cacerts} | Tail], Acc) when is_list(Cacerts) ->
     CacertsMsg = rabbit_data_coercion:to_utf8_binary(
         io_lib:format("(~b cacerts entries)", [length(Cacerts)])),
     format_socket_opts(Tail, [{cacerts, CacertsMsg} | Acc]);
 %% https://www.erlang.org/doc/apps/ssl/ssl.html#t:common_option_cert/0
 %% https://www.erlang.org/doc/apps/ssl/ssl.html#t:cert_key_conf/0
-format_socket_opts([{certs_keys, CertsKeys} | Tail], Acc)  ->
+format_socket_opts([{certs_keys, CertsKeys} | Tail], Acc) when is_map(CertsKeys) ->
     CertsKeysMsg = rabbit_data_coercion:to_utf8_binary(
         io_lib:format("(~b certs_keys entries)", [length(CertsKeys)])),
     format_socket_opts(Tail, [{cacerts, CertsKeysMsg} | Acc]);