polar plot legend bug

I get extraneous items in my legend if I have less than three datasets. I have a codepen example that demonstrates it.

Codepen example

If you change line 61 to:

var data = [trace1,trace2,trace3,trace4,trace5];
then you will see that the legend has no extraneous entries. I have been wrestling with this for a while but I am stumped :(
