Links to GPO from search results don't work

[lizadaly]

Not sure when this broke, but the API response from the backend doesn't return any values for GPO urls, so the front end has nothing to point to when the user tries to click the external links on the right:

Example from CAP:

<a data-v-5412d700="" href="https://cite.case.law/so-2d/782/339/" target="_blank" rel="noopener noreferrer">CAP</a>

Example from GPO:

<a data-v-5412d700="" target="_blank" rel="noopener noreferrer">GPO</a>

The API response isn't adding a url value here:

{"fullName": "Copies of Supplements to Code of Laws of United States and of District of Columbia Code and Supplements; conclusive evidence of original", 
"shortName": "Copies of Supplements to Code of Laws of United States and of District of Columbia C...", 
"fullCitations": "1 U.S.C. \u00a7 209", 
"shortCitations": "1 U.S.C. \u00a7 209", 
"effectiveDate": "2018-01-01", 
"url": null, 
"id": "USCODE-2018-title1-chap3-sec209"}

[lizadaly]

Fixed by removing the anchor when no link is present; if there could be a link here, it needs to be mapped from the data that we have.