Error when calling .addText() with array

[xtgdgwg]

be generated PowerPoint will require a "repair" operation to open the file. The file does not display correctly even when repaired.
PowerPoint 2016

[xtgdgwg]

I found out that the problem is not with the array but with the resulting XML format.
So I submitted a PR (#1083), can you see if there is a problem with this modification?
@gitbrent