NPM loader: KeyError: '1.0.2rc1' in project time metadata

Sentry Issue: SWH-LOADER-CORE-1P1

KeyError: '1.0.2rc1'
  File "swh/loader/package/loader.py", line 635, in load
    for branch_name, p_info in self.get_package_info(version):
  File "swh/loader/package/npm/loader.py", line 142, in get_package_info
    project_metadata=self.info(), version=version
  File "swh/loader/package/npm/loader.py", line 76, in from_metadata
    date = project_metadata["time"][extrinsic_version]

recurringly while loading https://www.npmjs.com/package/Sheet or https://www.npmjs.com/package/stack-component