Datahub: Remove warning from console if filter geometry undefined

[tkohr]

Description

This PR prevents displaying a warning in the console if no filter_geometry could be found (which is already logged in the console). This might occur when a request to the geometry aborts without success (due to access rights or a wrong url for example).

Follow-up on #635

Quality Assurance Checklist

• Commit history is devoid of any merge commits and readable to facilitate reviews
• If new logic ⚙️ is introduced: unit tests were added
• If new user stories 🤏 are introduced: E2E tests were added
• If new UI components 🕹️ are introduced: corresponding stories in Storybook were created
• If breaking changes 🪚 are introduced: add the breaking change label
• If bugs 🐞 are fixed: add the backport <release branch> label
• The documentation website 📚 has received the love it deserves

[github-actions]

Affected libs: feature-search, feature-router, feature-map, feature-dataviz, feature-record,
Affected apps: metadata-editor, datahub, demo, webcomponents, search, map-viewer,

• 🚀 Build and deploy storybook and demo on GitHub Pages
• 📦 Build and push affected docker images

[coveralls]

coverage: 86.054% (+2.1%) from 83.944%
when pulling 696ca82 on no-geom-no-error
into ca02804 on main.

[jahow]

Thanks! I made a few comments, also I think your idea about always returning null is good. In general the fix looks good so I'm approving, I hope the tests will eventually turn green...