I have a weird error that I seem to be having under Moodle 4.2 but not under Moodle 4.3.

I have set up a questionnaire with a rose graph. This is the error I get when trying to look at results:

Exception - implode(): Argument #1 ($pieces) must be of type array, string given

More information about this error
Debug info:
Error code: generalexceptionmessage×Dismiss this notification
Stack trace: * line 418 of /mod/questionnaire/drawchart.php: TypeError thrown

• line 418 of /mod/questionnaire/drawchart.php: call to implode()
• line 4018 of /mod/questionnaire/questionnaire.class.php: call to draw_chart()
• line 411 of /mod/questionnaire/questionnaire.class.php: call to questionnaire->response_analysis()
• line 271 of /mod/questionnaire/myreport.php: call to questionnaire->view_response()