fix(cyclonedx): add nil check to metadata.component

[masahiro331]

Description

Add nil check for "metadata.component"

Related issues

• Close SBOM unmarshalling does not deal with valid cyclonedx json #2654

Checklist

• I've read the guidelines for contributing to this repository.
• I've followed the conventions in the PR title.
• I've added tests that prove my fix is effective or that my feature works.
• I've updated the documentation with the relevant information (if needed).
• I've added usage information (if the PR introduces new options)
• I've included a "before" and "after" example to the description (if the PR is a user interface change).