Error curating component when license expressions contain empty element

Reproducing Steps:
1. Go to https://dev.clearlydefined.io/definitions/git/github/gardener/external-dns-management/ae804dcb1b3a49ded12169c694130993c68ced9f
2. Click the "SPDX license" place holder under Licensd.Declared to open License Expression editor
3. Select "MIT" license
4. Click Add Rule, select "Apache-2.0" license
5. Click Add Group, Click And, select "BSD-3-Clause" license
6. Save (see license expression image)
7. Click Contribute and fill out the contribution information and click OK.
8. Error in popup: Contribution ERROR: undefined:
`[{"coordinates":{"type":"git","provider":"github","namespace":"gardener","name":"external-dns-management","revision":"ae804dcb1b3a49ded12169c694130993c68ced9f"},"revisions":{"ae804dcb1b3a49ded12169c694130993c68ced9f":{"licensed":{"declared":"MIT AND Apache-2.0 AND BSD-3-Clause "}}}}]`