line continuation with sed

[Ray Andrews <rayandrews@xxxxxxxxxxx>]

I'm wondering if this is a zsh issue or entirely sed's fault but:

$ var=$( print -l $var | sed \
-re 's/.../' \                                 # this is fine
-re 's/.../'\                                  # this  throws an error 
which I'd expect
-re 's/.../' \                                  # this throws an error ...
-re 's/.../' )

... if there is a bloody space AFTER the backslash and before the 
newline.  Thing is it's an invisible error, I just wasted the morning 
with some sed errors which refused to be found because they were 
invisible.  What logic would make a space before the newline an error?  
I'm thinking it must be a zsh issue because zsh is responsible for line 
continuation.  Multiple spaces between sed expressions are fine as one 
would expect so if the backslash simply wrapped the line, there should 
be no issue.  Mind, haven't I whined about this before?  Could there 
ever be a situation where backslash-space-newline was not logically 
reducible to backslash-newline?  If there was such a thing, then of 
course my complaint is void.