StringIndexOutOfBoundsException during substring on a short-length string

java.lang.StringIndexOutOfBoundsException: String index out of range: 50
at java.lang.String.substring(String.java:1934)
at org.apache.hedwig.client.netty.ResponseHandler.messageReceived(ResponseHandler.java:124)
at org.jboss.netty.channel.Channels.fireMessageReceived(Channels.java:385)
at org.jboss.netty.handler.codec.oneone.OneToOneDecoder.handleUpstream(OneToOneDecoder.java:82)
at org.jboss.netty.channel.Channels.fireMessageReceived(Channels.java:385)
at org.jboss.netty.handler.codec.frame.FrameDecoder.unfoldAndFireMessageReceived(FrameDecoder.java:324)
at org.jboss.netty.handler.codec.frame.FrameDecoder.callDecode(FrameDecoder.java:306)
at org.jboss.netty.handler.codec.frame.FrameDecoder.messageReceived(FrameDecoder.java:223)
at org.jboss.netty.channel.Channels.fireMessageReceived(Channels.java:342)
at org.jboss.netty.channel.Channels.fireMessageReceived(Channels.java:329)
at org.jboss.netty.channel.socket.nio.NioWorker.read(NioWorker.java:330)
at org.jboss.netty.channel.socket.nio.NioWorker.processSelectedKeys(NioWorker.java:282)
at org.jboss.netty.channel.socket.nio.NioWorker.run(NioWorker.java:203)
at org.jboss.netty.util.internal.IoWorkerRunnable.run(IoWorkerRunnable.java:53)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:662)