Given a widget with a report saved in expert mode (with a working query)
when you edit this widget, switch to Default mode, select a tracker, edit the query for default mode, and hit "Search" button
then the widget will show the table of results, but there is a JavaScript error in the console:

cross-tracker-MLcMrbRV.js:19393 Uncaught (in promise) TypeError: Cannot read properties of undefined (reading 'find')
    at findArtifactSelectable (cross-tracker-MLcMrbRV.js:19393:14)
    at Object.mapReportToArtifactsTable (cross-tracker-MLcMrbRV.js:19520:14)

This error is due to the widget making two parallel requests to the API, once with default mode, and once with expert mode. Since the query can only be valid in one of the modes, one of the requests will fail.

Technical details

This is due to the design of the widget: it has two "artifact tables" that watch the report state. Only one is supposed to be mounted at a given time, but there is an interval after changing the widget state where both can be mounted at the same time, and trigger a request by their watch.