TypeError (String can't be coerced into Fixnum)?

I'm getting a weird error. My app runs perfectly fine on my localhost but on my Heroku server it's giving this error: TypeError (String can't be coerced into Fixnum):

Here is my code:

@rep = rep_score(@u)

According to the logs that's the line throwing the error. I've commented it out and pushed the changes to Heroku and the app runs fine now.

Here is the rep_score method:

def rep_score(user)
 rep = 0
 user.badges.each do |b|
   rep = rep + b.rep_bonus
 end
 return rep
end

Also rep_bonus is an integer in the database.

Again this runs perfectly fine on localhost. Let me know what you think.

After removing return from the rep_score method it's working fine. I'm still new to Ruby, is there something wrong with putting return? It's habit from other languages.