To avoid conflicts between d3v3, d3v4 and d3v5 htmlwidgets, every d3 instances have been renamed to d3v5, as suggested here : https://stackoverflow.com/a/44175830
In case of d3 upgrade, we have to replace t.d3=t.d3 by t.d3v5=t.d3v5 at the start of d3.min.js.