check names before creating User object (#48162)

(I don't know if creating the User object had any effet on the database
but better safe than sorry)

lib/account_controller_patch.rb

@@ -8,16 +8,16 @@ module AccountControllerNameCheckPatch
           @user = User.new(:language => current_language.to_s)
         else
           user_params = params[:user] || {}
-          @user = User.new
-          @user.safe_attributes = user_params
-          @user.pref.attributes = params[:pref] if params[:pref]
-          @user.admin = false
-          if @user.firstname == @user.lastname
+          if user_params[:firstname] == user_params[:lastname]
             # common spam pattern
             flash[:error] = "Error registering account."
             redirect_to home_url
             return
           end
+          @user = User.new
+          @user.safe_attributes = user_params
+          @user.pref.attributes = params[:pref] if params[:pref]
+          @user.admin = false
           @user.register
           if session[:auth_source_registration]
             @user.activate