Original stack trace:

NoMethodError: undefined method `unpack' for nil:NilClass
          byte! at /opt/logstash/vendor/bundle/jruby/1.9/gems/avro-1.8.2/lib/avro/io.rb:46
      read_long at /opt/logstash/vendor/bundle/jruby/1.9/gems/avro-1.8.2/lib/avro/io.rb:63
     read_union at /opt/logstash/vendor/bundle/jruby/1.9/gems/avro-1.8.2/lib/avro/io.rb:373
      read_data at /opt/logstash/vendor/bundle/jruby/1.9/gems/avro-1.8.2/lib/avro/io.rb:309
    read_record at /opt/logstash/vendor/bundle/jruby/1.9/gems/avro-1.8.2/lib/avro/io.rb:384
           each at org/jruby/RubyArray.java:1613
    read_record at /opt/logstash/vendor/bundle/jruby/1.9/gems/avro-1.8.2/lib/avro/io.rb:382
      read_data at /opt/logstash/vendor/bundle/jruby/1.9/gems/avro-1.8.2/lib/avro/io.rb:310
           read at /opt/logstash/vendor/bundle/jruby/1.9/gems/avro-1.8.2/lib/avro/io.rb:275
         decode at /opt/logstash/vendor/local_gems/70c8b815/logstash-codec-sbavro-2.0.4-java/lib/logstash/codecs/sbavro.rb:74
  thread_runner at /opt/logstash/vendor/bundle/jruby/1.9/gems/logstash-input-kafka-5.1.0/lib/logstash/inputs/kafka.rb:237
           each at file:/opt/logstash/vendor/jruby/lib/jruby.jar!/jruby/java/java_ext/java.lang.rb:12
  thread_runner at /opt/logstash/vendor/bundle/jruby/1.9/gems/logstash-input-kafka-5.1.0/lib/logstash/inputs/kafka.rb:236

Attempted to catch it:

      def byte!
        begin
            @reader.read(1).unpack('C').first
        rescue
            puts 'ERROR'
            puts @reader.inspect
        end
      end


new stack trace:

NoMethodError: undefined method `<<' for false:FalseClass
      read_long at /opt/logstash/vendor/bundle/jruby/1.9/gems/avro-1.8.2/lib/avro/io.rb:73
     read_union at /opt/logstash/vendor/bundle/jruby/1.9/gems/avro-1.8.2/lib/avro/io.rb:378
      read_data at /opt/logstash/vendor/bundle/jruby/1.9/gems/avro-1.8.2/lib/avro/io.rb:314
    read_record at /opt/logstash/vendor/bundle/jruby/1.9/gems/avro-1.8.2/lib/avro/io.rb:396
           each at org/jruby/RubyArray.java:1613
    read_record at /opt/logstash/vendor/bundle/jruby/1.9/gems/avro-1.8.2/lib/avro/io.rb:394
      read_data at /opt/logstash/vendor/bundle/jruby/1.9/gems/avro-1.8.2/lib/avro/io.rb:315
           read at /opt/logstash/vendor/bundle/jruby/1.9/gems/avro-1.8.2/lib/avro/io.rb:280
         decode at /opt/logstash/vendor/local_gems/e795cc97/logstash-codec-sbavro-2.0.4-java/lib/logstash/codecs/sbavro.rb:74
  thread_runner at /opt/logstash/vendor/bundle/jruby/1.9/gems/logstash-input-kafka-5.1.0/lib/logstash/inputs/kafka.rb:237
           each at file:/opt/logstash/vendor/jruby/lib/jruby.jar!/jruby/java/java_ext/java.lang.rb:12
  thread_runner at /opt/logstash/vendor/bundle/jruby/1.9/gems/logstash-input-kafka-5.1.0/lib/logstash/inputs/kafka.rb:236

where that error comes from:

        while (b & 0x80) != 0
          b = byte!
          n |= (b & 0x7F) << shift
          shift += 7
        end