cannot use strings in data in highcharts on doughnut charts - highcharts

Question

Why can't I use strings in data on a highchart doughnut chart? You can use it on Bar charts but not doughnut for some reason?
Example of strings in data for bar chart (no errors):
Fiddle: http://jsfiddle.net/8rsywuc7/
},
series: [{
name: 'John',
data: [5, 3, 4, 7, 2]
}, {
name: 'Jane',
data: ['','','','','']
}, {
name: 'Joe',
data: [3, 4, 4, 2, 5]
Example of strings in data for doughnut chart (see error):
Fiddle: http://jsfiddle.net/troqjcnz/
"data": [38, 44, 14, 20, 25, 75],
"name": "Male",
},
{
"data": ['','','','','',''],
"name": "Female",
},
{
"data": [38, 44, 14, 20, 25, 75],
"name": "No reply",
}

Answer 1

Notice that there is a big difference between those two series configs. In the first one, the data is an array of empty string, meanwhile in the second data becomes an array of objects where y is set to empty string. If you will do the same in the column, the same error will occur - see: http://jsfiddle.net/8rsywuc7/
series: [{
name: 'John',
data: [5, 3, 4, 7, 2]
}, {
name: 'Jane',
data: [{
name: 'test',
y: ''
}]
}, {
name: 'Joe',
data: [3, 4, 4, 2, 5]
}]
What can I suggest is:
use null rather than empty strings (I am aware that it is not the same, but the output should be similar), demo: http://jsfiddle.net/BlackLabel/jokbgryz/
change the logic responsible for creating data for something like is done here: http://jsfiddle.net/BlackLabel/9bov21gf/