nexus9 程序切换到后台，有时候异常崩溃

java.lang.NullPointerException 

Attempt to write to field 'java.lang.String com.easemob.chat.core.j$c.a' on a null object reference

com.easemob.chat.core.l.c(Unknown Source)
com.easemob.chat.core.n.i(Unknown Source)
com.easemob.chat.core.j.f(Unknown Source)
com.easemob.chat.core.EMConnectionManager.connect(Unknown Source)
com.easemob.chat.core.EMConnectionManager.connectSync(Unknown Source)
com.easemob.chat.core.EMConnectionManager.reconnectSync(Unknown Source)
com.easemob.chat.core.EMConnectionManager$3.run(Unknown Source)