[BUG] vcsim: crashes when object.collect specifies invalid property path

[Syuparn]

Describe the bug
vcsim crashes when govc object.collect is requested with invalid property path which is a property of an array property.

To Reproduce
Steps to reproduce the behavior:

1. run vcsim whthout any arguments
2. run commands below (note that config.hardware.device is an array and its properties cannot be obtained by this form)

# obtain vm's config.hardware.device, which is an array (this works as expected)
$ govc object.collect /DC0/vm/DC0_H0_VM0 config.hardware.device
config.hardware.device  []types.BaseVirtualDevice  ...

# try to obtain its property
$ govc object.collect /DC0/vm/DC0_H0_VM0 config.hardware.device.backing

Expected behavior
vcsim responds the InvalidProperty error.

$ govc object.collect /DC0/vm/DC0_H0_VM0 config.hardware.device.backing
govc: ServerFaultCode: InvalidProperty

Affected version

• vcsim 0.29.0

Screenshots/Debug Output

vcsim crashes by panic and govc responds EOF.

$ vcsim
export GOVC_URL=https://user:pass@127.0.0.1:8989/sdk GOVC_SIM_PID=11048
2022/09/19 15:37:03 http: panic serving 127.0.0.1:54212: reflect: call of reflect.Value.FieldByName on slice Value
goroutine 81 [running]:
net/http.(*conn).serve.func1()
        /opt/hostedtoolcache/go/1.18.3/x64/src/net/http/server.go:1825 +0xbf
panic({0xd23780, 0xc00053b020})
        /opt/hostedtoolcache/go/1.18.3/x64/src/runtime/panic.go:844 +0x258
reflect.flag.mustBe(...)
        /opt/hostedtoolcache/go/1.18.3/x64/src/reflect/value.go:223
reflect.Value.FieldByName({0xc9ce20?, 0xc0001c42d8?, 0xf7b629?}, {0xc000010ae1?, 0x0?})
        /opt/hostedtoolcache/go/1.18.3/x64/src/reflect/value.go:1297 +0x1d6
github.com/vmware/govmomi/simulator.fieldValue({0xf61f80?, 0xc0001d6000?, 0xc00022ab60?}, {0xc00022ab60?, 0x38?})
        /home/runner/work/govmomi/govmomi/simulator/property_collector.go:184 +0x39c
github.com/vmware/govmomi/simulator.(*retrieveResult).collectFields(0xf61f80?, 0xc0008053b0, {0xf61f80?, 0xc0001d6000?, 0xbbc338?}, {0xc000031f90, 0x1, 0x40?}, 0xc00052d860)
        /home/runner/work/govmomi/govmomi/simulator/property_collector.go:307 +0x217
github.com/vmware/govmomi/simulator.(*retrieveResult).collect(0xc0009065a8, 0x20?, {{0xc00021ce40?, 0xc0000bfd70?}, {0xc00021ce63?, 0xc0008053b0?}})
        /home/runner/work/govmomi/govmomi/simulator/property_collector.go:358 +0x814
github.com/vmware/govmomi/simulator.(*PropertyCollector).collect.func2()
        /home/runner/work/govmomi/govmomi/simulator/property_collector.go:441 +0x34
github.com/vmware/govmomi/simulator.(*Registry).WithLock(0xee26c0?, 0x0?, {0x1121a00?, 0xc0005017a0?}, 0xc000906588)
        /home/runner/work/govmomi/govmomi/simulator/registry.go:634 +0x37
github.com/vmware/govmomi/simulator.(*Context).WithLock(...)
        /home/runner/work/govmomi/govmomi/simulator/session_manager.go:382
github.com/vmware/govmomi/simulator.(*PropertyCollector).collect(0xee4ac0?, 0xc0008053b0, 0xc0009067a0)
        /home/runner/work/govmomi/govmomi/simulator/property_collector.go:441 +0x207
github.com/vmware/govmomi/simulator.(*PropertyCollector).apply(0xc00012f020, 0xc0008053b0, 0xc00044eff0)
        /home/runner/work/govmomi/govmomi/simulator/property_collector.go:597 +0x218
github.com/vmware/govmomi/simulator.(*PropertyCollector).WaitForUpdatesEx.func1()
        /home/runner/work/govmomi/govmomi/simulator/property_collector.go:661 +0x32
github.com/vmware/govmomi/simulator.(*PropertyCollector).WaitForUpdatesEx(0xc00012f020, 0xc0008053b0, 0xc0001dd800)
        /home/runner/work/govmomi/govmomi/simulator/property_collector.go:671 +0x33a
reflect.Value.call({0xf4aa00?, 0xc00012f020?, 0x18?}, {0xf7bdc7, 0x4}, {0xc00044ef60, 0x2, 0xc000907320?})
        /opt/hostedtoolcache/go/1.18.3/x64/src/reflect/value.go:556 +0x845
reflect.Value.Call({0xf4aa00?, 0xc00012f020?, 0x44b7b4?}, {0xc00044ef60, 0x2, 0x2})
        /opt/hostedtoolcache/go/1.18.3/x64/src/reflect/value.go:339 +0xbf
github.com/vmware/govmomi/simulator.(*Service).call.func1()
        /home/runner/work/govmomi/govmomi/simulator/simulator.go:218 +0x3a
github.com/vmware/govmomi/simulator.(*Registry).WithLock(0xf78600?, 0xc00053afa8?, {0x111c520?, 0xc00012f020?}, 0xc0009075b8)
        /home/runner/work/govmomi/govmomi/simulator/registry.go:634 +0x37
github.com/vmware/govmomi/simulator.(*Service).call(0xc00007e540, 0xc0008053b0, 0xc00054d480)
        /home/runner/work/govmomi/govmomi/simulator/simulator.go:217 +0xf10
github.com/vmware/govmomi/simulator.(*Service).ServeSDK(0xc00007e540, {0x1123c70, 0xc000255ea0}, 0xc0005c3600)
        /home/runner/work/govmomi/govmomi/simulator/simulator.go:492 +0x549
net/http.HandlerFunc.ServeHTTP(0xbc71482f627baab2?, {0x1123c70?, 0xc000255ea0?}, 0x0?)
        /opt/hostedtoolcache/go/1.18.3/x64/src/net/http/server.go:2084 +0x2f
net/http.(*ServeMux).ServeHTTP(0x0?, {0x1123c70, 0xc000255ea0}, 0xc0005c3600)
        /opt/hostedtoolcache/go/1.18.3/x64/src/net/http/server.go:2462 +0x149
net/http.serverHandler.ServeHTTP({0x1122d88?}, {0x1123c70, 0xc000255ea0}, 0xc0005c3600)
        /opt/hostedtoolcache/go/1.18.3/x64/src/net/http/server.go:2916 +0x43b
net/http.(*conn).serve(0xc0001da280, {0x1124060, 0xc0002080c0})
        /opt/hostedtoolcache/go/1.18.3/x64/src/net/http/server.go:1966 +0x5d7
created by net/http.(*Server).Serve
        /opt/hostedtoolcache/go/1.18.3/x64/src/net/http/server.go:3071 +0x4db

$ govc object.collect /DC0/vm/DC0_H0_VM0 config.hardware.device.backing
govc: Post "https://127.0.0.1:8989/sdk": EOF

Additional context

[Syuparn]

By the way, is there any way to obtain specific properties of an array property? If it exists, vcsim should also handle this.

[github-actions]

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