Editor encounters unexpected error when adding blocks

XAMPP on macOS 10.13.6
php 7.3.1
WordPress 5.3.2
Download Manager 3.0.8
WPDM – Gutenberg Blocks 1.3.3

Actions:
– Open existing Post for editing (Block Editor) OR Create new Post (Block Editor)
– Add new ‘Package’ block

Expected Behaviour:
– New Block is added and ready for editing

Actual Behaviour:
The editor has encountered an unexpected error.

Additional Information:
‘Attempt recovery’ button produces a blank editor screen (i.e. recovery is unsuccessful)
‘Copy Error’ button produces the following log (URL changed for security)

TypeError: Cannot read property 'map' of null
    at PackageList.render (http://example.com/wp-content/plugins/wpdm-gutenberg-blocks/js/libs/package-selector.js?ver=5.3.2:29:34)
    at re (http://example.com/wp-includes/js/dist/vendor/react-dom.min.js?ver=16.9.0:95:261)
    at Vg (http://example.com/wp-includes/js/dist/vendor/react-dom.min.js?ver=16.9.0:95:54)
    at ph (http://example.com/wp-includes/js/dist/vendor/react-dom.min.js?ver=16.9.0:217:70)
    at lh (http://example.com/wp-includes/js/dist/vendor/react-dom.min.js?ver=16.9.0:126:409)
    at O (http://example.com/wp-includes/js/dist/vendor/react-dom.min.js?ver=16.9.0:121:71)
    at ze (http://example.com/wp-includes/js/dist/vendor/react-dom.min.js?ver=16.9.0:118:14)
    at http://example.com/wp-includes/js/dist/vendor/react-dom.min.js?ver=16.9.0:53:49
    at unstable_runWithPriority (http://example.com/wp-includes/js/dist/vendor/react.min.js?ver=16.9.0:26:340)
    at Ma (http://example.com/wp-includes/js/dist/vendor/react-dom.min.js?ver=16.9.0:52:280)