Fix completion error when command is empty

[feloy]

What type of PR is this:

/kind bug

What does this PR do / why we need it:

Which issue(s) this PR fixes:

Fixes #6353

PR acceptance criteria:

• Unit test

• Integration test

• Documentation

How to test changes / Special notes to the reviewer:

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[rm3l]

/approve

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

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[openshift-ci]

New changes are detected. LGTM label has been removed.

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Kudos, SonarCloud Quality Gate passed!   

0 Bugs
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0.0% Duplication

[rm3l]

Expected
      <*url.Error | 0xc0002e0120>: {
          Op: "Post",
          URL: "http://127.0.0.1:56448/api/newuser",
          Err: <*errors.errorString | 0xc000184100>{s: "EOF"},
      }
  to be nil
  In [It] at: C:/Users/Administrator.ANSIBLE-TEST-VS/2637/tests/e2escenarios/e2e_test.go:287

Overriding because the previous test run passed with the same changes.

/override windows-integration-test/Windows-test

[openshift-ci]

@rm3l: Overrode contexts on behalf of rm3l: windows-integration-test/Windows-test

In response to this:

Expected
     <*url.Error | 0xc0002e0120>: {
         Op: "Post",
         URL: "http://127.0.0.1:56448/api/newuser",
         Err: <*errors.errorString | 0xc000184100>{s: "EOF"},
     }
 to be nil
 In [It] at: C:/Users/Administrator.ANSIBLE-TEST-VS/2637/tests/e2escenarios/e2e_test.go:287

Overriding because the previous test run passed with the same changes.

/override windows-integration-test/Windows-test

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.

[rm3l]

/override ci/prow/v4.11-integration-e2e

All tests are passing on IBM Cloud.

[openshift-ci]

@rm3l: Overrode contexts on behalf of rm3l: ci/prow/v4.11-integration-e2e

In response to this:

/override ci/prow/v4.11-integration-e2e

All tests are passing on IBM Cloud.

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.