client: fix returning the wrong error
client: fix returning the wrong error

err goes out of scope at the end of the if-block

Bug found with ineffassign.

remerge/sarama,vrischmann/sarama,raisemarketplace/sarama,raisemarketplace/sarama,Shopify/sarama,VividCortex/sarama,DataDog/sarama,remerge/sarama,mailgun/sarama,vrischmann/sarama,VividCortex/sarama,HelixEducation/sarama,HelixEducation/sarama,mailgun/sarama,DataDog/sarama,Shopify/sarama