3D Structure chooser fails to select structures from 3D-beacons and pops up a 'null' dialog

Discovering structures for some uniprot entries result in a dialog popping up with 'null' in the message area. These seem to result from an empty JSON doc being returned by 3d-beacons:

https://www.ebi.ac.uk/pdbe/pdbe-kb/3dbeacons/api/uniprot/summary/P0DTD3.json

This raises unexpected exceptions:
java.lang.NullPointerException
at jalview.gui.structurechooser.TDBResultAnalyser.getFilteredResponse(TDBResultAnalyser.java:134)
at jalview.gui.structurechooser.ThreeDBStructureChooserQuerySource.selectFirstRankedQuery(ThreeDBStructureChooserQuerySource.java:361)
at jalview.gui.StructureChooser$7.run(StructureChooser.java:567)
at java.lang.Thread.run(Thread.java:750)