LinkValidator threw exception

Description

Steps to reproduce: 

1. Install Alloy.
2. Update EPiServer.CMS package to 11.15.1.
3. Compile and build.
4. On start page, add a Button block in a content area.
5. Enter required text.
6. In link, click external and paste the JavaScript:
   javascript:void(location.href='mailto:' + String.fromCharCode(106,111,104,97,110,46,97,110,116,105,108,97,64,111,112,116,105,109,105,122,101,108,121,46,99,111,109))
7. Save and publish block and page.
8. Go to admin.
9. Run Link Validator job.

An exception caused the job to fail and stop executing, instead of marking it as an invalid link and ignoring it going forward, to complete with a summary of scanned links and failed links.