I Need to know How to fix this.

Sometimes Server is Nulling

Code:
 java.lang.NullPointerException
E: 	at client.rightClickCheck(client.java:246)
E: 	at client.process(client.java:19037)
E: 	at PlayerHandler.process(PlayerHandler.java:262)
E: 	at process.run(process.java:23)
E: 	at java.lang.Thread.run(Thread.java:619)
E: java.lang.NullPointerException
E: 	at misc.playerNameToInt64(misc.java:171)
E: 	at client.initialize(client.java:12144)
E: 	at PlayerHandler.process(PlayerHandler.java:311)
E: 	at process.run(process.java:23)
E: 	at java.lang.Thread.run(Thread.java:619)
E: java.lang.NullPointerException
E: 	at client.logout(client.java:12660)
E: 	at PlayerHandler.saveGame(PlayerHandler.java:361)
E: 	at PlayerHandler.process(PlayerHandler.java:298)
E: 	at process.run(process.java:23)
E: 	at java.lang.Thread.run(Thread.java:619)