Nil pointer error when a SecurityPolicy refers to a UDS Backend

[zhaohuabing]

apiVersion: gateway.envoyproxy.io/v1alpha1
kind: Backend
metadata:
  name: ext-auth-svc
spec:
  endpoints:
  - unix:
      path: /var/run/envoy-uds/ext-auth.sock
---

apiVersion: gateway.envoyproxy.io/v1alpha1
kind: SecurityPolicy
metadata:
  name: ext-auth-poc
spec:
  extAuth:
    failOpen: false
    http:
      backendRefs:
      - group: gateway.envoyproxy.io
        kind: Backend
        name: ext-auth-svc
      headersToBackend:
      - x-current-user
    recomputeRoute: true
  targetRefs:
  - group: gateway.networking.k8s.io
    kind: HTTPRoute
    name: ext-auth-poc

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x2768705]

goroutine 305 [running]:
github.com/envoyproxy/gateway/internal/gatewayapi.backendRefAuthority(0xc0011169c0?, 0xc002a781e8, 0x7?)
	/home/runner/work/gateway/gateway/internal/gatewayapi/securitypolicy.go:960 +0x185
github.com/envoyproxy/gateway/internal/gatewayapi.(*Translator).buildExtAuth(0x78f5d88?, 0xc0010c9380, 0xc002e28c88, 0xc003199140?)
	/home/runner/work/gateway/gateway/internal/gatewayapi/securitypolicy.go:908 +0x3b6
github.com/envoyproxy/gateway/internal/gatewayapi.(*Translator).translateSecurityPolicyForRoute(0xc002a798f8, 0xc0010c9380, {0x78f5d88, 0xc002ca6bc0}, 0xc002e28c88, 0xc000ad7290)
	/home/runner/work/gateway/gateway/internal/gatewayapi/securitypolicy.go:373 +0x677
github.com/envoyproxy/gateway/internal/gatewayapi.(*Translator).ProcessSecurityPolicies(0xc002a798f8, {0xc0000cd598, 0x1, 0x1}, {0xc00333e428, 0x1, 0x1}, {0xc003199570, 0x1, 0x1}, ...)
	/home/runner/work/gateway/gateway/internal/gatewayapi/securitypolicy.go:150 +0x1931
github.com/envoyproxy/gateway/internal/gatewayapi.(*Translator).Translate(0xc002a798f8, 0xc002e28c88)
	/home/runner/work/gateway/gateway/internal/gatewayapi/translator.go:217 +0xaa5
github.com/envoyproxy/gateway/internal/gatewayapi/runner.(*Runner).subscribeAndTranslate.func1({{0xc000135e30?, 0x0?}, 0x2?, 0xc0031a65b8?}, 0xc001039490)
	/home/runner/work/gateway/gateway/internal/gatewayapi/runner/runner.go:167 +0x42c
github.com/envoyproxy/gateway/internal/message.HandleSubscription[...]({{0x3254be7, 0xb?}, {0x3266e8a?, 0x12?}}, 0xc0010351f0?, 0xc002a79f98)
	/home/runner/work/gateway/gateway/internal/message/watchutil.go:76 +0x1118
github.com/envoyproxy/gateway/internal/gatewayapi/runner.(*Runner).subscribeAndTranslate(0xc002315200, {0x78babb0?, 0xc001202000?})
	/home/runner/work/gateway/gateway/internal/gatewayapi/runner/runner.go:119 +0x7e
created by github.com/envoyproxy/gateway/internal/gatewayapi/runner.(*Runner).Start in goroutine 137
	/home/runner/work/gateway/gateway/internal/gatewayapi/runner/runner.go:85 +0x2a5