Problem:
When creating a report with a stacked bar visualization and then removing the secondary groupBy so that there are no more stacked bars, switching to a pie chart visualization breaks the report.

Reproduce:

• Create a bar chart report that can have stacked bars, e.g. process instance count, grouped by start date and variable
• Enable Stacked Bars
• Remove the secondary group by
• Switch to a Pie Chart Visualization

Expected:

• Pie Chart is displayed

Observed:

• Report crashes with "Cannot read properties of undefined (reading 'axis')"