Panic when there are no pods

[howardjohn]

panic: invalid argument to Intn

goroutine 254 [running]:
math/rand.(*Rand).Intn(0x945e60?, 0xc0000007e0?)
        /usr/local/go/src/math/rand/rand.go:180 +0x4c
math/rand.Intn(0x0)
        /usr/local/go/src/math/rand/rand.go:464 +0x25
sigs.k8s.io/gateway-api-inference-extension/pkg/epp/handlers.GetRandomPod({0x252f350?, 0xc0006ee000?})
        /src/pkg/epp/handlers/server.go:452 +0x34
sigs.k8s.io/gateway-api-inference-extension/pkg/epp/handlers.(*StreamingServer).HandleRequestHeaders(0xc0007bd9c0, {0x0?, 0x0?}, 0xc000b958c0, 0xc0006ae118)
        /src/pkg/epp/handlers/request.go:140 +0x78
sigs.k8s.io/gateway-api-inference-extension/pkg/epp/handlers.(*StreamingServer).Process(0xc0007bd9c0, {0x2526288, 0xc00090eba0})
        /src/pkg/epp/handlers/server.go:161 +0x3d7
github.com/envoyproxy/go-control-plane/envoy/service/ext_proc/v3._ExternalProcessor_Process_Handler({0x1f96f40?, 0xc0007bd9c0}, {0x2521598, 0xc0000007e0})
        /go/pkg/mod/github.com/envoyproxy/go-control-plane/[email protected]/service/ext_proc/v3/external_processor_grpc.pb.go:106 +0xd8
google.golang.org/grpc.(*Server).processStreamingRPC(0xc000253000, {0x251a070, 0xc00090bc20}, 0xc000a86b40, 0xc00082faa0, 0x37c80e0, 0x0)
        /go/pkg/mod/google.golang.org/[email protected]/server.go:1695 +0x1252
google.golang.org/grpc.(*Server).handleStream(0xc000253000, {0x251ab10, 0xc000830340}, 0xc000a86b40)
        /go/pkg/mod/google.golang.org/[email protected]/server.go:1819 +0xb47
google.golang.org/grpc.(*Server).serveStreams.func2.1()
        /go/pkg/mod/google.golang.org/[email protected]/server.go:1035 +0x7f
created by google.golang.org/grpc.(*Server).serveStreams.func2 in goroutine 253
        /go/pkg/mod/google.golang.org/[email protected]/server.go:1046 +0x11d

Looks like we don't handle the case of there being no pods available