Application Crash on qbChatDialog.sendMessage(chatMessage);

Question

Environment details (Operating system, browser information, SDK version) Android, SDK: 3.20

Expected behavior when I login in an application and chat with other users it's working fine but once I exit from an application and start again and sending a message in chat dialog application crash.

Actual behavior application should not crash.

Logs (please, use github gist)

FATAL EXCEPTION: main
Process: com.bhads.ibuy, PID: 7295
java.lang.IllegalStateException: Could not execute method for android:onClick
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:293)
at android.view.View.performClick(View.java:4780)
at android.view.View$PerformClick.run(View.java:19866)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5254)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288)
at android.view.View.performClick(View.java:4780)
at android.view.View$PerformClick.run(View.java:19866)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5254)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void com.quickblox.chat.QBAbstractChat.sendMessage(com.quickblox.chat.model.QBChatMessage)' on a null object reference
at com.quickblox.chat.model.QBChatDialog.sendMessage(SourceFile:506)
at com.bhads.ibuy.ui.activity.ChatActivity.sendChatMessage(ChatActivity.java:364)
at com.bhads.ibuy.ui.activity.ChatActivity.onSendChatClick(ChatActivity.java:287)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288)
at android.view.View.performClick(View.java:4780)
at android.view.View$PerformClick.run(View.java:19866)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5254)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)

Steps to reproduce the behavior -> Login in application -> sending message in the user dialog -> exit from application (kill from background also) -> start application again -> go to the dialog list activity and select dialog -> type message and click on send button , APPLICATION IS CRASH

Any others comments? I also did reloginToChat(user) and it gives Success response. and also set following properties in chat helper class

qbChatService.setDefaultPacketReplyTimeout(150000); //add this
qbChatService.setDefaultConnectionTimeout(150000);
qbChatService.setDefaultAutoSendPresenceInterval(60);

QBChatService.ConfigurationBuilder chatServiceConfigurationBuilder = new QBChatService.ConfigurationBuilder();
chatServiceConfigurationBuilder.setSocketTimeout(60); 
chatServiceConfigurationBuilder.setKeepAlive(true); 
chatServiceConfigurationBuilder.setUseTls(true); 
QBChatService.setConfigurationBuilder(chatServiceConfigurationBuilder);