Description of expected behavior and the observed behavior
Code raises exception instead of correctly rendering with matplotlib.
Strangely enough, in some notebook a plot is still displayed, but in some others the plot is not displayed at all.
Complete, minimal, self-contained example code that reproduces the issue
import holoviews as hv
hv.extension('matplotlib')
# Removing either the HLine or the label avoid the exception
hv.Rectangles([(0,0,1,1), (2,2,3,3)], label='hello') * hv.HLine(3)
ALL software version info
holoviews: 1.14.4 jupyterlab: 2.3.1 bokeh: 2.3.2 matplotlib: 3.4.2
Description of expected behavior and the observed behavior
Code raises exception instead of correctly rendering with matplotlib. Strangely enough, in some notebook a plot is still displayed, but in some others the plot is not displayed at all.
Complete, minimal, self-contained example code that reproduces the issue
Stack traceback and/or browser JavaScript console output
Screenshots or screencasts of the bug in action