fix: report an error when route table name is not configured

[feiskyer]

What type of PR is this?

/kind cleanup

What this PR does / why we need it:

fix: report an error when route table name is not configured. Without this fix, cloud controller manager would crash on such scenarios.

Which issue(s) this PR fixes:

Fixes #756

Special notes for your reviewer:

Does this PR introduce a user-facing change?

fix: report an error when route table name is not configured

Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

[coveralls]

Coverage increased (+0.004%) to 80.619% when pulling 55b97f3 on feiskyer:fix-route into f871993 on kubernetes-sigs:master.

[andyzhangx]

/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: andyzhangx, feiskyer

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• OWNERS [andyzhangx,feiskyer]

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[MartinForReal]

/cherrypick release-1.1

[MartinForReal]

/cherrypick release-1.0

[k8s-infra-cherrypick-robot]

@MartinForReal: new pull request created: #1428

In response to this:

/cherrypick release-1.1

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[k8s-infra-cherrypick-robot]

@MartinForReal: new pull request created: #1429

In response to this:

/cherrypick release-1.0

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.