[client] Don't choke on non-existent interface in route updates

[lixmal]

Describe your changes

Improves debugging in cases like #2742

Issue ticket number and link

Checklist

• [x] Is it a bug fix
• [ ] Is a typo/documentation fix
• [ ] Is a feature enhancement
• [ ] It is a refactor
• [ ] Created tests that fail without the change (if possible)
• [ ] Extended the README / documentation, if necessary

[sonarcloud[bot]]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud