There seems to be a bug in PolarExtrude component when using FullCircle = True. In some cases, the circle is closed as expected, while in many cases there is a bug, leaving a gap open:
In my example
gaps appear for the follwoing numbers: 8,12,14,15,17,18,20
no gaps appear for the follwoing numbers: 4,5,6,7,9,10,11,13,16,19
To me this looks like a bug in the angle calculation, in case FullCircle = True is used.
Here is a screenshot of the setup:
And here is the GH file for your reference:
polarextrude_bug.gh (8.9 KB)