Prettify nested error messages

[m1k1o]

When using custom hooks and calling multiple decode functions, error output is not really human readable:

19 error(s) decoding:

* '' has invalid keys: log
* cannot parse 'transport.disable_compression' as bool: strconv.ParseBool: parsing "<bool>": invalid syntax
* cannot parse 'transport.disable_keep_alives' as bool: strconv.ParseBool: parsing "<bool>": invalid syntax
* cannot parse 'transport.force_attempt_http2' as bool: strconv.ParseBool: parsing "<bool>": invalid syntax
* cannot parse 'transport.max_conns_per_host' as int: strconv.ParseInt: parsing "<int>": invalid syntax
* cannot parse 'transport.max_idle_conns' as int: strconv.ParseInt: parsing "<int>": invalid syntax
* cannot parse 'transport.max_idle_conns_per_host' as int: strconv.ParseInt: parsing "<int>": invalid syntax
* cannot parse 'transport.max_response_header_bytes' as int: strconv.ParseInt: parsing "<int64>": invalid syntax
* cannot parse 'transport.read_buffer_size' as int: strconv.ParseInt: parsing "<int>": invalid syntax
* cannot parse 'transport.write_buffer_size' as int: strconv.ParseInt: parsing "<int>": invalid syntax
* error decoding 'proxy.middlewares[0]': failed to unmarshal provider cache: 1 error(s) decoding:

* error decoding 'provider': failed to unmarshal provider memory: 1 error(s) decoding:

* '' has invalid keys: ttl
* error decoding 'proxy.providers[1]': failed to unmarshal provider http: 1 error(s) decoding:

* '' has invalid keys: proxy
* error decoding 'proxy.providers[2]': failed to unmarshal provider hls: 1 error(s) decoding:

* error decoding 'proxy.middlewares[0]': failed to unmarshal provider cache: 1 error(s) decoding:

* error decoding 'provider': failed to unmarshal provider memory: 1 error(s) decoding:

* '' has invalid keys: ttl
* error decoding 'transport.dial_keep_alive': time: invalid duration "<time.Duration>"
* error decoding 'transport.dial_timeout': time: invalid duration "<time.Duration>"
* error decoding 'transport.expect_continue_timeout': time: invalid duration "<time.Duration>"
* error decoding 'transport.idle_conn_timeout': time: invalid duration "<time.Duration>"
* error decoding 'transport.response_header_timeout': time: invalid duration "<time.Duration>"
* error decoding 'transport.tls_handshake_timeout': time: invalid duration "<time.Duration>"

Changing to more readable format:

command execution finished with error: failed to unmarshal service config: 19 error(s) decoding:
* cannot parse 'transport.disable_compression' as bool: strconv.ParseBool: parsing "<bool>": invalid syntax
* cannot parse 'transport.disable_keep_alives' as bool: strconv.ParseBool: parsing "<bool>": invalid syntax
* cannot parse 'transport.force_attempt_http2' as bool: strconv.ParseBool: parsing "<bool>": invalid syntax
* cannot parse 'transport.max_conns_per_host' as int: strconv.ParseInt: parsing "<int>": invalid syntax
* cannot parse 'transport.max_idle_conns' as int: strconv.ParseInt: parsing "<int>": invalid syntax
* cannot parse 'transport.max_idle_conns_per_host' as int: strconv.ParseInt: parsing "<int>": invalid syntax
* cannot parse 'transport.max_response_header_bytes' as int: strconv.ParseInt: parsing "<int64>": invalid syntax
* cannot parse 'transport.read_buffer_size' as int: strconv.ParseInt: parsing "<int>": invalid syntax
* cannot parse 'transport.write_buffer_size' as int: strconv.ParseInt: parsing "<int>": invalid syntax
* error decoding 'proxy.middlewares[0]': failed to unmarshal provider cache: 1 error(s) decoding:
  * error decoding 'provider': failed to unmarshal provider memory: 1 error(s) decoding:
    * invalid keys: ttl
* error decoding 'proxy.providers[1]': failed to unmarshal provider http: 1 error(s) decoding:
  * invalid keys: proxy
* error decoding 'proxy.providers[2]': failed to unmarshal provider hls: 1 error(s) decoding:
  * error decoding 'proxy.middlewares[0]': failed to unmarshal provider cache: 1 error(s) decoding:
    * error decoding 'provider': failed to unmarshal provider memory: 1 error(s) decoding:
      * invalid keys: ttl
* error decoding 'transport.dial_keep_alive': time: invalid duration "<time.Duration>"
* error decoding 'transport.dial_timeout': time: invalid duration "<time.Duration>"
* error decoding 'transport.expect_continue_timeout': time: invalid duration "<time.Duration>"
* error decoding 'transport.idle_conn_timeout': time: invalid duration "<time.Duration>"
* error decoding 'transport.response_header_timeout': time: invalid duration "<time.Duration>"
* error decoding 'transport.tls_handshake_timeout': time: invalid duration "<time.Duration>"