nans cause traces to disappear in newer pyqt5
Missing data or infs are replaced by nans, and then those are supposed to not be displayed when using the
connect='finite' option to setData plot.py:#L329. However, a bug in recent versions of pyqt5 cause the entire trace to not display if there is any nan in the to-be-displayed data.
It's apparently an upstream issue: https://github.com/pyqtgraph/pyqtgraph/issues/1057
This seems to affect pyqt5 5.15.0 in Debian bullseye but not 5.11.3 in buster.