hook runtime error: invalid memory address or nil pointer dereference

[NickUfer]

Describe the bug

I configured a webhook for after registration. Kratos serves a 503 response.

Reproducing the bug

Steps to reproduce the behavior:

Server logs

2021/10/25 22:39:41 http: panic serving 10.88.0.1:53506: runtime error: invalid memory address or nil pointer dereference
goroutine 115 [running]:
net/http.(*conn).serve.func1(0xc0000b0140)
	/usr/local/go/src/net/http/server.go:1824 +0x153
panic(0x1560460, 0x2317060)
	/usr/local/go/src/runtime/panic.go:971 +0x499
bytes.(*Reader).Len(...)
	/usr/local/go/src/bytes/reader.go:27
net/http.NewRequestWithContext(0x19eb4a8, 0xc000040060, 0xc000766508, 0x4, 0xc00143f120, 0x1b, 0x19c3b40, 0x0, 0x0, 0x19c4b40, ...)
	/usr/local/go/src/net/http/request.go:897 +0x435
net/http.NewRequest(...)
	/usr/local/go/src/net/http/request.go:828
github.com/ory/kratos/selfservice/hook.doHttpCall(0xc000766508, 0x4, 0xc00143f120, 0x1b, 0x19c4b40, 0x2512c88, 0x19c3b40, 0x0, 0x40e398, 0x40)
	/home/ory/selfservice/hook/web_hook.go:311 +0x99
github.com/ory/kratos/selfservice/hook.(*WebHook).execute(0xc0009a6ae0, 0xc000188180, 0x0, 0x0)
	/home/ory/selfservice/hook/web_hook.go:266 +0x208
github.com/ory/kratos/selfservice/hook.(*WebHook).ExecutePostRegistrationPostPersistHook(0xc0009a6ae0, 0x7f820f33ef08, 0xc00000e278, 0xc001124b00, 0xc000900680, 0xc001528460, 0x3, 0x4)
	/home/ory/selfservice/hook/web_hook.go:229 +0xd4
github.com/ory/kratos/selfservice/flow/registration.(*HookExecutor).PostRegistrationHook(0xc00117aa10, 0x7f820f33ef08, 0xc00000e278, 0xc001124b00, 0x176085e, 0x8, 0xc000900680, 0xc000a5c000, 0x1627da0, 0xc000d00000)
	/home/ory/selfservice/flow/registration/hook.go:143 +0xc79
github.com/ory/kratos/selfservice/flow/registration.(*Handler).submitFlow(0xc000ada6b0, 0x7f820f33ef08, 0xc00000e278, 0xc001124b00, 0x0, 0x0, 0x0)
	/home/ory/selfservice/flow/registration/handler.go:407 +0x5e8
github.com/ory/kratos/session.(*Handler).IsNotAuthenticated.func1(0x7f820f33ef08, 0xc00000e278, 0xc001124b00, 0x0, 0x0, 0x0)
	/home/ory/session/handler.go:176 +0x48c
github.com/ory/kratos/x.NoCacheHandler.func1(0x7f820f33ef08, 0xc00000e278, 0xc001124b00, 0x0, 0x0, 0x0)
	/home/ory/x/nocache.go:18 +0x83
github.com/julienschmidt/httprouter.(*Router).ServeHTTP(0xc000aac5a0, 0x7f820f33ef08, 0xc00000e278, 0xc001124b00)
	/go/pkg/mod/github.com/julienschmidt/[email protected]/router.go:387 +0xc7e
github.com/ory/nosurf.(*CSRFHandler).handleSuccess(...)
	/go/pkg/mod/github.com/ory/[email protected]/handler.go:201
github.com/ory/nosurf.(*CSRFHandler).ServeHTTP(0xc0001b4e70, 0x7f820f33ef08, 0xc00000e278, 0xc001124a00)
	/go/pkg/mod/github.com/ory/[email protected]/handler.go:152 +0x7b0
github.com/urfave/negroni.Wrap.func1(0x7f820f33ef08, 0xc00000e278, 0xc001124a00, 0xc000128100)
	/go/pkg/mod/github.com/urfave/[email protected]/negroni.go:46 +0x4d
github.com/urfave/negroni.HandlerFunc.ServeHTTP(0xc000a90d20, 0x7f820f33ef08, 0xc00000e278, 0xc001124a00, 0xc000128100)
	/go/pkg/mod/github.com/urfave/[email protected]/negroni.go:29 +0x4e
github.com/urfave/negroni.middleware.ServeHTTP(0x19c80a0, 0xc000a90d20, 0xc000a911d0, 0x7f820f33ef08, 0xc00000e278, 0xc001124a00)
	/go/pkg/mod/github.com/urfave/[email protected]/negroni.go:38 +0x9c
github.com/ory/kratos/x.glob..func1(0x7f820f33ef08, 0xc00000e278, 0xc001124a00, 0xc0001280e0)
	/home/ory/x/clean_url.go:12 +0x8b
github.com/urfave/negroni.HandlerFunc.ServeHTTP(0x1843e60, 0x7f820f33ef08, 0xc00000e278, 0xc001124a00, 0xc0001280e0)
	/go/pkg/mod/github.com/urfave/[email protected]/negroni.go:29 +0x4e
github.com/urfave/negroni.middleware.ServeHTTP(0x19c80a0, 0x1843e60, 0xc000a911b8, 0x7f820f33ef08, 0xc00000e278, 0xc001124a00)
	/go/pkg/mod/github.com/urfave/[email protected]/negroni.go:38 +0x9c
github.com/urfave/negroni.(*Negroni).ServeHTTP(0xc000691aa0, 0x19e4fd8, 0xc000d9c7e0, 0xc001124a00)
	/go/pkg/mod/github.com/urfave/[email protected]/negroni.go:96 +0xf1
github.com/rs/cors.(*Cors).Handler.func1(0x19e4fd8, 0xc000d9c7e0, 0xc001124a00)
	/go/pkg/mod/github.com/rs/[email protected]/cors.go:207 +0x1b1
net/http.HandlerFunc.ServeHTTP(0xc000a6c100, 0x19e4fd8, 0xc000d9c7e0, 0xc001124a00)
	/usr/local/go/src/net/http/server.go:2069 +0x44
net/http.serverHandler.ServeHTTP(0xc000ae00e0, 0x19e4fd8, 0xc000d9c7e0, 0xc001124a00)
	/usr/local/go/src/net/http/server.go:2887 +0xa3
net/http.(*conn).serve(0xc0000b0140, 0x19eb518, 0xc000188400)
	/usr/local/go/src/net/http/server.go:1952 +0x8cd
created by net/http.(*Server).Serve
	/usr/local/go/src/net/http/server.go:3013 +0x39b

Server configuration

version: v0.7.6-alpha.1

dsn: postgres://user:[email protected]:5432/kratos?sslmode=disable

serve:
  public:
    base_url: https://example.com/
    cors:
      enabled: true
  admin:
    base_url: http://kratos:4434/

selfservice:
  default_browser_return_url: https://example.com/
  whitelisted_return_urls:
    - https://example.com

  methods:
    password:
      enabled: true

  flows:
    error:
      ui_url: https://example.com/error

    settings:
      ui_url: https://example.com/settings
      privileged_session_max_age: 15m

    recovery:
      enabled: true
      ui_url: https://example.com/recovery

    verification:
      enabled: true
      ui_url: https://example.com/verify
      after:
        default_browser_return_url: https://example.com/

    logout:
      after:
        default_browser_return_url: https://example.com/auth/login

    login:
      ui_url: https://example.com/auth/login
      lifespan: 10m

    registration:
      lifespan: 10m
      ui_url: https://example.com/auth/register
      after:
        password:
          hooks:
            - hook: web_hook
              config:
                url: 'https://example.com/somewebhook'
                method: 'GET'
            - hook: session

log:
  level: info
  format: text
  leak_sensitive_values: true

secrets:
  cookie:
    - omitted

hashers:
  argon2:
    parallelism: 1
    memory: 128MB
    iterations: 2
    salt_length: 16
    key_length: 16

identity:
  default_schema_url: file:///etc/kratos/schemas/v1/person.schema.json

courier:
  smtp:
    connection_uri: smtps://test:test@mailslurper:1025/?skip_ssl_verify=true&legacy_ssl=true

Expected behavior

The webhook is called.

Environment

• Version: v0.7.6
• Environment: Docker