They would previously cause error while attempting to save the warp to a file.
Now periods will not be allowed in warp names. There is a separate new message for such cases when creating a warp.
New message:
Code (yalm (Unknown Language)):
name-cannot-have-period: '&cThe name of the warp &6{name}&c cointains a period (&7.&c) which is not allowed'
Thanks to
@AcornMC for bringing this to my attention.