I was also surprised to see that she was credited as a producer.
Good catch! Summer as well as Jesse Bradford are listed as producers. You'll notice the writers and director are also credited as executive/supervising producers. I'm pretty sure it has nothing to do with a traditional producer's role, they probably provided some kind of help in the creative/writing process.
Currently, because of the restrictions the Writers Guild of America screenwriting credit system places on writing credits, many script writers are credited as "producers" instead, even though they may not engage in the responsibilities generally associated with that title.