Steps to reproduce:

1. Create trapper item
2. Send data as 0
3. Create pie chart widget with this item
4. Check result

Result:
The Pie chart widget displays "No data", but this is not true, because data exists and is equal to 0. Also the legend is not displayed.
Expected:
the pie chart is all filled out

I created 3 examples: item without data, Item with data = 0, Item with data = 0.01