fix panic due to empty gw

[Abirdcfly]

What type of PR is this?
/kind bug

What this PR does / why we need it:

I1010 16:32:46.078267       1 tunnel.go:131] [MDNS] Discovery found peer: {12D3KooWFzqKr5PhTuKCsry9Cyo3DtvMDrK5HenyTfRMzDgyCraL: [/ip4/172.31.10.125/tcp/20006 /ip4/169.254.25.10/tcp/20006 /ip4/127.0.0.1/tcp/20006 /ip4/10.62.48.116/tcp/20006]}
panic: runtime error: index out of range [0] with length 0

goroutine 764 [running]:
github.com/kubeedge/edgemesh/pkg/gateway.(*Server).newProto.func1({0x3b01d68?, 0x1f55d80?}, {0x2153880?, 0xc0008ee880?})
        /code/pkg/gateway/server.go:164 +0x1a7
sync.(*Map).Range(0x3b01d60?, 0xc000717b38)
        /usr/local/go/src/sync/map.go:354 +0x2b8
github.com/kubeedge/edgemesh/pkg/gateway/cache.RangeVirtualServices(...)
        /code/pkg/gateway/cache/cache.go:73
github.com/kubeedge/edgemesh/pkg/gateway.(*Server).newProto(0xc00066d5f0, {0x2737c98?, 0xc00037a078})
        /code/pkg/gateway/server.go:171 +0xa6
github.com/kubeedge/edgemesh/pkg/gateway.(*Server).serve(0xc00066d5f0)
        /code/pkg/gateway/server.go:142 +0x925
created by github.com/kubeedge/edgemesh/pkg/gateway.NewServer
        /code/pkg/gateway/server.go:68 +0x165

when there is a gw that Spec.Gateways is empty, there is a panic, note this gateway may not related with kubeedge, it is may just normal istio gateway

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

NONE

[gemini-code-assist]

Summary of Changes

Hello @Abirdcfly, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request resolves a critical bug in the edgemesh gateway component that caused a runtime panic. The panic was triggered when the system attempted to access the first element of an empty Spec.Gateways slice within a VirtualService object. The fix introduces a defensive check to ensure the slice is not empty before indexing, thereby preventing the "index out of range" error and improving the stability of the gateway's virtual service discovery.

Highlights

• Panic Fix: Addressed a runtime panic that occurred when processing VirtualService objects with an empty Spec.Gateways field, preventing an "index out of range" error.

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[gemini-code-assist]

Code Review

This pull request addresses a panic caused by accessing an empty Spec.Gateways slice in a virtual service. The fix correctly adds a bounds check before accessing the slice. My review includes a suggestion to further improve the logic by iterating through all gateways in the list, rather than just checking the first one, to ensure correct behavior when a virtual service is associated with multiple gateways.

[gemini-code-assist]

While your change correctly prevents the panic, it only considers the first gateway listed in vs.Spec.Gateways. A VirtualService can be bound to multiple gateways, and this implementation will fail to find a match if the intended gateway is not the first in the list.

To make the logic more robust and align with the intended behavior of virtual services, I suggest iterating over the vs.Spec.Gateways slice to check for a match.

for _, gw := range vs.Spec.Gateways {
					if gw == srv.options.GwName && reflect.DeepEqual(vs.Spec.Hosts, srv.options.Hosts) {
						vss = append(vss, vs)
						break
					}
				}