Edge cases in eventplot are likely broken #7560
Description
The eventplot code currently contains the snippet
if len(lineoffsets) == 0:
lineoffsets = [None]
if len(linelengths) == 0:
linelengths = [None]
if len(linewidths) == 0:
lineoffsets = [None] # oops
if len(linewidths) == 0:
lineoffsets = [None] # oops
if len(colors) == 0:
colors = [None]
which is certainly incorrect.