Bug: failed loki insert

Describe the bug
if log line is json the insertion would fail

{"level":"error","ts":"2025-09-28T12:21:44.721518Z","logger":"fd.loki.output.loki","message":"can't send data to Loki","address":"http://localhost:3100","error":"bad response: code=400, err=response status from http://localhost:3100/loki/api/v1/push isn't OK: status=400, body=loghttp.PushRequest.Streams: []loghttp.LogProtoStream: unmarshalerDecoder: Value is string, but can't find closing '\"' symbol, error found in #10 byte of ...|:38660}]]}]}|..., bigger context ...|tocol\":\"HTTP/2.0\",\"status\":\"304\",\"bytes\":38660}]]}]}|...\n"}
{"level":"error","ts":"2025-09-28T12:21:44.722507Z","logger":"fd.loki.output.loki","message":"can't send data to Loki","address":"http://localhost:3100","error":"bad response: code=400, err=response status from http://localhost:3100/loki/api/v1/push isn't OK: status=400, body=loghttp.PushRequest.Streams: []loghttp.LogProtoStream: unmarshalerDecoder: Value is string, but can't find closing '\"' symbol, error found in #10 byte of ...|:17003}]]}]}|..., bigger context ...|tocol\":\"HTTP/2.0\",\"status\":\"503\",\"bytes\":17003}]]}]}|...\n"}
{"level":"error","ts":"2025-09-28T12:21:44.72251Z","logger":"fd.loki.output.loki","message":"can't send data to Loki","address":"http://localhost:3100","error":"bad response: code=400, err=response status from http://localhost:3100/loki/api/v1/push isn't OK: status=400, body=loghttp.PushRequest.Streams: []loghttp.LogProtoStream: unmarshalerDecoder: Value is string, but can't find closing '\"' symbol, error found in #10 byte of ...|\":2521}]]}]}|..., bigger context ...|otocol\":\"HTTP/1.0\",\"status\":\"410\",\"bytes\":2521}]]}]}|...\n"}
{"level":"error","ts":"2025-09-28T12:21:44.72286Z","logger":"fd.loki.output.loki","message":"can't send data to Loki","address":"http://localhost:3100","error":"bad response: code=400, err=response status from http://localhost:3100/loki/api/v1/push isn't OK: status=400, body=loghttp.PushRequest.Streams: []loghttp.LogProtoStream: unmarshalerDecoder: Value is string, but can't find closing '\"' symbol, error found in #10 byte of ...|:26831}]]}]}|..., bigger context ...|tocol\":\"HTTP/1.1\",\"status\":\"200\",\"bytes\":26831}]]}]}|...\n"}
{"level":"error","ts":"2025-09-28T12:21:44.725175Z","logger":"fd.loki.output.loki","message":"can't send data to Loki","address":"http://localhost:3100","error":"bad response: code=400, err=response status from http://localhost:3100/loki/api/v1/push isn't OK: status=400, body=loghttp.PushRequest.Streams: []loghttp.LogProtoStream: unmarshalerDecoder: Value is string, but can't find closing '\"' symbol, error found in #10 byte of ...|:42978}]]}]}|..., bigger context ...|tocol\":\"HTTP/1.0\",\"status\":\"404\",\"bytes\":42978}]]}]}|...\n"}
{"level":"error","ts":"2025-09-28T12:21:44.725769Z","logger":"fd.loki.output.loki","message":"can't send data to Loki","address":"http://localhost:3100","error":"bad response: code=400, err=response status from http://localhost:3100/loki/api/v1/push isn't OK: status=400, body=loghttp.PushRequest.Streams: []loghttp.LogProtoStream: unmarshalerDecoder: Value is string, but can't find closing '\"' symbol, error found in #10 byte of ...|:41531}]]}]}|..., bigger context ...|tocol\":\"HTTP/1.0\",\"status\":\"301\",\"bytes\":41531}]]}]}|...\n"}
{"level":"error","ts":"2025-09-28T12:21:44.985293Z","logger":"fd.loki.output.loki","message":"can't send data to Loki","address":"http://localhost:3100","error":"bad response: code=400, err=response status from http://localhost:3100/loki/api/v1/push isn't OK: status=400, body=loghttp.PushRequest.Streams: []loghttp.LogProtoStream: unmarshalerDecoder: Value is string, but can't find closing '\"' symbol, error found in #10 byte of ...|:22297}]]}]}|..., bigger context ...|\"HTTP/1.1\",\"status\":\"300\",\"bytes\":22297}]]}]}|...\n"}

To Reproduce
Steps to reproduce the behavior:

1. file.d --config=./config.yaml
2. config.yaml

pipelines:
  loki:
    settings:
      capacity: 1000
    input:
      type: file
      persistence_mode: async
      # offsets_op: reset
      paths:
        include:
          - '/Users/romanchechyotkin/file.d/demo_logs.json'
      offsets_file: ./offsets.yaml
    actions:
      - type: json_decode
        field: message
      - type: set_time
        field: timestamp
        override: false
      - type: convert_date
        field: timestamp
        target_format: unixtimenano
        source_formats:
        - 'rfc3339'
        - 'rfc3339nano'
        - '02/Jan/2006:15:04:05 -0700'
        - '2006-01-02T15:04:05.999Z0700'
    output:
      type: loki
      fatal_on_failed_insert: true
      retry: 3
      address: http://localhost:3100
      timestamp_field: timestamp
      message_field: message

3. demo_logs.json

{"host":"localhost","message":"{\"host\":\"143.61.119.90\",\"user-identifier\":\"jesseddy\",\"datetime\":\"22/Sep/2025:17:25:23\",\"method\":\"HEAD\",\"request\":\"/user/booperbot124\",\"protocol\":\"HTTP/1.0\",\"status\":\"404\",\"bytes\":14476,\"referer\":\"https://we.bauhaus/wp-admin\"}","service":"vector","source_type":"demo_logs","timestamp":"2025-09-22T10:25:23.842787109Z"}
{"host":"localhost","message":"{\"host\":\"53.108.32.5\",\"user-identifier\":\"KarimMove\",\"datetime\":\"22/Sep/2025:17:25:24\",\"method\":\"DELETE\",\"request\":\"/wp-admin\",\"protocol\":\"HTTP/1.1\",\"status\":\"503\",\"bytes\":28124,\"referer\":\"https://random.xn--ses554g/wp-admin\"}","service":"vector","source_type":"demo_logs","timestamp":"2025-09-22T10:25:24.842790741Z"}
{"host":"localhost","message":"{\"host\":\"84.243.110.238\",\"user-identifier\":\"jesseddy\",\"datetime\":\"22/Sep/2025:17:25:25\",\"method\":\"PATCH\",\"request\":\"/secret-info/open-sesame\",\"protocol\":\"HTTP/2.0\",\"status\":\"300\",\"bytes\":9760,\"referer\":\"https://for.sharp/this/endpoint/prints/money\"}","service":"vector","source_type":"demo_logs","timestamp":"2025-09-22T10:25:25.843117222Z"}
{"host":"localhost","message":"{\"host\":\"38.66.28.220\",\"user-identifier\":\"KarimMove\",\"datetime\":\"22/Sep/2025:17:25:26\",\"method\":\"PATCH\",\"request\":\"/booper/bopper/mooper/mopper\",\"protocol\":\"HTTP/2.0\",\"status\":\"302\",\"bytes\":39540,\"referer\":\"https://up.mint/secret-info/open-sesame\"}","service":"vector","source_type":"demo_logs","timestamp":"2025-09-22T10:25:26.842443312Z"}
{"host":"localhost","message":"{\"host\":\"95.224.105.65\",\"user-identifier\":\"AnthraX\",\"datetime\":\"22/Sep/2025:17:25:27\",\"method\":\"PATCH\",\"request\":\"/controller/setup\",\"protocol\":\"HTTP/1.1\",\"status\":\"501\",\"bytes\":36475,\"referer\":\"https://some.coffee/user/booperbot124\"}","service":"vector","source_type":"demo_logs","timestamp":"2025-09-22T10:25:27.842764515Z"}
{"host":"localhost","message":"{\"host\":\"197.162.35.153\",\"user-identifier\":\"AnthraX\",\"datetime\":\"22/Sep/2025:17:25:28\",\"method\":\"HEAD\",\"request\":\"/secret-info/open-sesame\",\"protocol\":\"HTTP/1.0\",\"status\":\"550\",\"bytes\":34609,\"referer\":\"https://make.itau/this/endpoint/prints/money\"}","service":"vector","source_type":"demo_logs","timestamp":"2025-09-22T10:25:28.842343264Z"}
{"host":"localhost","message":"{\"host\":\"225.215.17.246\",\"user-identifier\":\"meln1ks\",\"datetime\":\"22/Sep/2025:17:25:29\",\"method\":\"HEAD\",\"request\":\"/do-not-access/needs-work\",\"protocol\":\"HTTP/1.0\",\"status\":\"300\",\"bytes\":11504,\"referer\":\"https://make.visa/observability/metrics/production\"}","service":"vector","source_type":"demo_logs","timestamp":"2025-09-22T10:25:29.842516190Z"}
{"host":"localhost","message":"{\"host\":\"44.104.173.118\",\"user-identifier\":\"meln1ks\",\"datetime\":\"22/Sep/2025:17:25:30\",\"method\":\"PATCH\",\"request\":\"/do-not-access/needs-work\",\"protocol\":\"HTTP/2.0\",\"status\":\"501\",\"bytes\":29462,\"referer\":\"https://for.casa/user/booperbot124\"}","service":"vector","source_type":"demo_logs","timestamp":"2025-09-22T10:25:30.842455780Z"}
{"host":"localhost","message":"{\"host\":\"94.238.133.67\",\"user-identifier\":\"AnthraX\",\"datetime\":\"22/Sep/2025:17:25:31\",\"method\":\"POST\",\"request\":\"/secret-info/open-sesame\",\"protocol\":\"HTTP/2.0\",\"status\":\"401\",\"bytes\":49266,\"referer\":\"https://for.careers/this/endpoint/prints/money\"}","service":"vector","source_type":"demo_logs","timestamp":"2025-09-22T10:25:31.842494758Z"}
{"host":"localhost","message":"{\"host\":\"32.198.110.120\",\"user-identifier\":\"KarimMove\",\"datetime\":\"22/Sep/2025:17:25:32\",\"method\":\"PATCH\",\"request\":\"/apps/deploy\",\"protocol\":\"HTTP/2.0\",\"status\":\"307\",\"bytes\":2102,\"referer\":\"https://for.supplies/controller/setup\"}","service":"vector","source_type":"demo_logs","timestamp":"2025-09-22T10:25:32.842482780Z"}
{"host":"localhost","message":"{\"host\":\"156.48.43.166\",\"user-identifier\":\"b0rnc0nfused\",\"datetime\":\"22/Sep/2025:17:25:33\",\"method\":\"PATCH\",\"request\":\"/this/endpoint/prints/money\",\"protocol\":\"HTTP/1.1\",\"status\":\"550\",\"bytes\":6737,\"referer\":\"https://up.scholarships/do-not-access/needs-work\"}","service":"vector","source_type":"demo_logs","timestamp":"2025-09-22T10:25:33.842276138Z"}
{"host":"localhost","message":"{\"host\":\"240.16.218.38\",\"user-identifier\":\"BronzeGamer\",\"datetime\":\"22/Sep/2025:17:25:34\",\"method\":\"PATCH\",\"request\":\"/booper/bopper/mooper/mopper\",\"protocol\":\"HTTP/1.1\",\"status\":\"501\",\"bytes\":24455,\"referer\":\"https://up.ru/wp-admin\"}","service":"vector","source_type":"demo_logs","timestamp":"2025-09-22T10:25:34.842712690Z"}
{"host":"localhost","message":"{\"host\":\"111.115.2.95\",\"user-identifier\":\"AnthraX\",\"datetime\":\"22/Sep/2025:17:25:35\",\"method\":\"OPTION\",\"request\":\"/booper/bopper/mooper/mopper\",\"protocol\":\"HTTP/2.0\",\"status\":\"501\",\"bytes\":47782,\"referer\":\"https://we.bom/booper/bopper/mooper/mopper\"}","service":"vector","source_type":"demo_logs","timestamp":"2025-09-22T10:25:35.842652357Z"}
{"host":"localhost","message":"{\"host\":\"225.242.176.18\",\"user-identifier\":\"AmbientTech\",\"datetime\":\"22/Sep/2025:17:25:36\",\"method\":\"GET\",\"request\":\"/booper/bopper/mooper/mopper\",\"protocol\":\"HTTP/2.0\",\"status\":\"400\",\"bytes\":17510,\"referer\":\"https://for.us/wp-admin\"}","service":"vector","source_type":"demo_logs","timestamp":"2025-09-22T10:25:36.842563338Z"}
{"host":"localhost","message":"{\"host\":\"54.103.95.172\",\"user-identifier\":\"b0rnc0nfused\",\"datetime\":\"22/Sep/2025:17:25:37\",\"method\":\"HEAD\",\"request\":\"/secret-info/open-sesame\",\"protocol\":\"HTTP/1.0\",\"status\":\"403\",\"bytes\":37313,\"referer\":\"https://make.statebank/wp-admin\"}","service":"vector","source_type":"demo_logs","timestamp":"2025-09-22T10:25:37.843126765Z"}
{"host":"localhost","message":"{\"host\":\"154.115.115.219\",\"user-identifier\":\"AnthraX\",\"datetime\":\"22/Sep/2025:17:25:38\",\"method\":\"POST\",\"request\":\"/do-not-access/needs-work\",\"protocol\":\"HTTP/2.0\",\"status\":\"200\",\"bytes\":33917,\"referer\":\"https://up.sarl/controller/setup\"}","service":"vector","source_type":"demo_logs","timestamp":"2025-09-22T10:25:38.842404698Z"}
{"host":"localhost","message":"{\"host\":\"5.61.15.83\",\"user-identifier\":\"KarimMove\",\"datetime\":\"22/Sep/2025:17:25:39\",\"method\":\"GET\",\"request\":\"/observability/metrics/production\",\"protocol\":\"HTTP/1.0\",\"status\":\"401\",\"bytes\":7104,\"referer\":\"https://make.mo/wp-admin\"}","service":"vector","source_type":"demo_logs","timestamp":"2025-09-22T10:25:39.842595810Z"}

Expected behavior
Successful insert

Additional context
Main latest build

Start with the file.d entry point and reproduce the failure using config.yaml, demo_logs.json, and the Loki output settings shown. Trace how json_decode transforms the message before insertion and verify the behavior against the provided nested JSON logs. Done means the same configuration successfully inserts the records into Loki.