Patch: https://github.com/Wikidata-lib/PropertySuggester/pull/175

The cause here is that we do the search for suggestions whenever the property input field is empty and gets focused. As it gets focused twice whenever a new statement is added, we load the suggestions twice and (due to a race condition) even sometimes display them twice. The fix for this is simple: Only load the suggestions one the very first focus, the base suggester will then do the right things for us, when the field's value changes.