Error when metadata is incomplete

[m10k]

When generating SBOMs for some packages, alma-sbom fails with the following error.

Traceback (most recent call last):
  File "/root/alma-sbom/./alma_sbom.py", line 612, in <module>
    cli_main()
  File "/root/alma-sbom/./alma_sbom.py", line 594, in cli_main
    sbom = get_info_about_package(
  File "/root/alma-sbom/./alma_sbom.py", line 300, in get_info_about_package
    'value': immudb_metadata['build_host'],
KeyError: 'build_host'

Steps to reproduce:

$ dnf download bc-1.07.1-14.el9.x86_64
$ hash=$(sha256sum bc-1.07.1-14.el9.x86_64.rpm | cut -d ' ' -f 1)
$ ./alma_sbom.py --file-format spdx-json --rpm-package-hash "$hash"

This is what immudb_metadata looks like:

{
  "arch": "x86_64",
  "epoch": "0",
  "git_commit": "36ba399613061e6190966c2e97f23fdf7e061cce",
  "git_ref": "imports/c9/bc-1.07.1-14.el9",
  "git_url": "https://git.almalinux.org/rpms/bc.git",
  "name": "bc",
  "release": "14.el9",
  "sbom_api": "0.2",
  "source_type": "git",
  "sourcerpm": "bc-1.07.1-14.el9.src.rpm",
  "version": "1.07.1"
}

I imagine that the metadata for some packages is incomplete because they were built with older versions of ALBS. Maybe we should omit missing data from SBOM generation and only fail if NTIA Minimum Elements are missing?