hyperv: Check for Get-Wmiobject err before parsing output

[tstromberg]

Right after I merged #7790 I realized the PR didn't check for err first.

Also, update the error message handling because Get-Wmiobject only returns an error if it's unavailable to make a local RPC, rather than if the object is not found. Proof that this PR works, in lieu of working Hyper-V integration tests:

$ ./out/minikube.exe start
* minikube v1.10.0-beta.0 on Microsoft Windows 10 Pro 10.0.19041 Build 19041
* Automatically selected the hyperv driver
* Starting control plane node minikube in cluster minikube
* Creating hyperv VM (CPUs=2, Memory=6000MB, Disk=20000MB) ...
* Preparing Kubernetes v1.18.0 on Docker 19.03.8 ...
* Verifying Kubernetes components...
* Enabled addons: default-storageclass, storage-provisioner
* Done! kubectl is now configured to use "minikube"

[k8s-ci-robot]

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This pull-request has been approved by: tstromberg

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[tstromberg]

/ok-to-test

[minikube-pr-bot]

kvm2 Driver
docker Driver

[minikube-pr-bot]

kvm2 Driver
Times for minikube: [65.447123905 66.379941643 68.001651202]
Average time for minikube: 66.60957225

Times for Minikube (PR 7867): [65.264037659 66.926832696 64.172406678]
Average time for Minikube (PR 7867): 65.45442567766668

Averages Time Per Log

+--------------------------------+-----------+--------------------+
|              LOG               | MINIKUBE  | MINIKUBE (PR 7867) |
+--------------------------------+-----------+--------------------+
| * minikube v1.10.0-beta.1 on   |  0.058299 |           0.059078 |
| Debian 9.11                    |           |                    |
| * Using the kvm2 driver based  |  0.020631 |           0.021046 |
| on existing profile            |           |                    |
| * Starting control plane node  |  0.003334 |           0.003487 |
| minikube in cluster minikube   |           |                    |
| * Creating kvm2 VM (CPUs=2,    | 41.487044 |          41.411888 |
| Memory=3700MB, Disk=20000MB)   |           |                    |
| ...                            |           |                    |
| * Preparing Kubernetes v1.18.0 | 22.663770 |          21.834807 |
| on Docker 19.03.8 ...          |           |                    |
| * Verifying Kubernetes         |  1.481860 |           1.804108 |
| components...                  |           |                    |
| * Enabled addons:              |  0.818752 |           0.241412 |
| default-storageclass,          |           |                    |
| storage-provisioner            |           |                    |
| * Done! kubectl is now         |  0.072731 |           0.074809 |
| configured to use "minikube"   |           |                    |
|                                |  0.003151 |           0.003793 |
+--------------------------------+-----------+--------------------+

docker Driver
Times for minikube: [26.73674339 27.246530462000003 27.284693852999997]
Average time for minikube: 27.08932256833333

Times for Minikube (PR 7867): [26.969211379 29.477531361 25.979742795]
Average time for Minikube (PR 7867): 27.475495178333333

Averages Time Per Log

+----------------------------------------+-----------+--------------------+
|                  LOG                   | MINIKUBE  | MINIKUBE (PR 7867) |
+----------------------------------------+-----------+--------------------+
| * minikube v1.10.0-beta.1 on           |  0.075512 |           0.077483 |
| Debian 9.11                            |           |                    |
| * Using the docker driver              |  0.002740 |           0.002565 |
| based on existing profile              |           |                    |
| * Starting control plane node          |  0.060341 |           0.058305 |
| minikube in cluster minikube           |           |                    |
| * Creating docker container            |  7.921210 |           7.693496 |
| (CPUs=2, Memory=3700MB) ...            |           |                    |
| * Preparing Kubernetes v1.18.0         |  0.000223 |           0.000232 |
| on Docker 19.03.2 ...                  |           |                    |
|   -                                    | 18.126316 |          18.320715 |
| kubeadm.pod-network-cidr=10.244.0.0/16 |           |                    |
| * Verifying Kubernetes                 |  0.832353 |           1.138058 |
| components...                          |           |                    |
| * Enabled addons:                      |  0.002919 |           0.115249 |
| default-storageclass,                  |           |                    |
| storage-provisioner                    |           |                    |
| * Done! kubectl is now                 |  0.063261 |           0.064604 |
| configured to use "minikube"           |           |                    |
|                                        |  0.004448 |           0.004788 |
+----------------------------------------+-----------+--------------------+