stops after until-loop if i reaches @cpus.size. why?

until-bug.rb

def getBetter()
        puts "getBetter"
        puts "@cpus.length: #{@cpus.length}"
        puts "current cpu: #{self.cpu.type}"
    
        begin
            i = @cpus.index(self.cpu) + 0     # this only works if cpu is taken from this instance of @cpus
        rescue Exception => e
            @cpus.each do |cpu|
                if cpu.type == self.cpu.type
                    i = @cpus.index(cpu)
                    break
                end 
            end
            puts "rescue-end"
        end
        puts "after cpu-rescue"
        until i > @cpus.size
            i += 1
            puts "i: #{i}"
            puts "#{@cpus[i].type}"
            puts "self.cpu.normalizedRating: #{self.cpu.normalizedRating}"
            puts " @cpus[i].normalizedRating: #{@cpus[i].normalizedRating}"
            
            if @cpus[i].normalizedRating > self.cpu.normalizedRating
                puts "setting cpu to: #{@cpus[i].type}"
                cpu = @cpus[i]
                # @cpus and @gpus are sorted by price, so the first better one is good enough
                puts "breaking"
                break
            end
        end
        puts "done with cpus"
        begin
            i = @gpus.index(self.gpu) + 0
        rescue Exception => e
            @gpus.each do |gpu|
                if gpu.type == self.gpu.type
                    i = @gpus.index(gpu)
                    break
                end 
            end
        end
        puts "i: #{i}"
        puts "@gpus.size: #{@gpus.size}"
        
        until i > @gpus.size
            i += 1
            if @gpus[i].normalizedRating > self.gpu.normalizedRating
                gpu = @gpus[i]
                break
            end
        end
        rec = Recommendation.new
        rec.cpu = cpu
        rec.gpu = gpu
        return rec
    end