Kong declarative configuration error: attempt to index field 'consumer' (a nil value)

Questions
1

I used declarative configuration instead of a database for configuration of Kong. Everything had been working fine until I tried to add JWT authentication configuarition in /etc/kong/kong.yml.

Declarative Configuration (/etc/kong/kong.yml):

_format_version: "1.1"

services:
- name: serverinfo
  url: http://profile.facebook.service.com:9090
  # Entities can store tags as metadata
  tags:
  - serverinfo
  # Entities that have a foreign-key relationship can be nested:
  routes:
  - name: serverinfo-route
    paths:
    - /serverinfo
  plugins:
  - name: http-log
    config:
        http_endpoint: http://localhost:9900/log
        method: POST
        timeout: 1000
        keepalive: 1000
- name: certs
  url: http://localhost:68766
  tags:
  - certs
  routes:
  - name: certs-route
    paths:
    - /kong/answers
  plugins:
  - name: jwt
    config:

consumers:
- username: jessie_pinkman
  jwt_secrets:
  - key: walter_white
  - secret: youwannacook?

routes:
- name: serverinfo-route
  # Relationships can also be specified between top-level entities,
  # either by name or by id
  service: serverinfo
  hosts: ["profile.facebook.service.com"]
- name: certs-route
  # Relationships can also be specified between top-level entities,
  # either by name or by id
  service: certs
  hosts: ["profile.stackoverflow.com"]

plugins:
- name: http-log
  service: serverinfo
  config: 
    http_endpoint: http://localhost:9900/log
    method: POST
    timeout: 1000
    keepalive: 1000

- name: jwt
  service: certs
  consumer: jessie_pinkman
  config:

jwt_secrets:
- key: walter_white
  secret: youwannacook?
  algorithm: HS256

Reloading Kong:

http :8001/config config=@kong.yml

Access service:

curl -X POST \
  http://127.0.0.1:8000/kong/answers \
  -H 'Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyLCJpc3MiOiJ3YWx0ZXJfd2hpdGUifQ.4oidCCnrHcfYkbwC0lvCMAKnxiht07cUzI1oOxWAk78' \
  -H 'Content-Type: application/json' \
  -H 'Host: profile.stackoverflow.com' \
  -H 'username: jessie_pinkman' \
  -d '{"id":1}'

Error from /usr/local/kong/logs/error.log:

[error] 1097#0: *23738 lua coroutine: runtime error: /usr/local/share/lua/5.1/kong/plugins/jwt/handler.lua:209: attempt to index field 'consumer' (a nil value)
stack traceback:
coroutine 0:
        /usr/local/share/lua/5.1/kong/plugins/jwt/handler.lua: in function 'do_authentication'
        /usr/local/share/lua/5.1/kong/plugins/jwt/handler.lua:244: in function </usr/local/share/lua/5.1/kong/plugins/jwt/handler.lua:232>
coroutine 1:
        [C]: in function 'resume'
        coroutine.wrap:21: in function <coroutine.wrap:21>
        /usr/local/share/lua/5.1/kong/init.lua:663: in function 'access'
        access_by_lua(nginx-kong.conf:102):2: in function <access_by_lua(nginx-kong.conf:102):1>, client: 127.0.0.1, server: kong, request: "POST /kong/answers HTTP/1.1", host: "profile.stackoverflow.com"
2019/08/05 20:21:48 [error] 1097#0: *23738 [kong] init.lua:669 /usr/local/share/lua/5.1/kong/plugins/jwt/handler.lua:209: attempt to index field 'consumer' (a nil value), client: 127.0.0.1, server: kong, request: "POST /kong/answers HTTP/1.1", host: "profile.stackoverflow.com"