Yes, you’d better to make sure the field types are the same. Because qChartView needs to merge the data from two list, if it find the common column that has the same field name but different data types, that may throw the exception during merging data.
For your case, I think the Choice type can be supported, because the internal value of this field type is string. You could take a try. If you can provide your list and web part temples, I can do the test for you.