Avoid NPE when access table.jsp and snapshot.jsp but master not finish initialization

2019-07-16,11:11:56,895 WARN [qtp1930319715-581] org.eclipse.jetty.servlet.ServletHandler: /table.jsp
java.lang.NullPointerException
at org.apache.hadoop.hbase.generated.master.table_jsp._jspService(table_jsp.java:154)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:111)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:840)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1780)
at org.apache.hadoop.hbase.http.lib.StaticUserWebFilter$StaticUserFilter.doFilter(StaticUserWebFilter.java:112)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1767)
at org.apache.hadoop.hbase.http.ClickjackingPreventionFilter.doFilter(ClickjackingPreventionFilter.java:48)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1767)
at org.apache.hadoop.hbase.http.HttpServer$QuotingInputFilter.doFilter(HttpServer.java:1428)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1767)
at org.apache.hadoop.hbase.http.NoCacheFilter.doFilter(NoCacheFilter.java:50)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1767)
at org.apache.hadoop.hbase.http.NoCacheFilter.doFilter(NoCacheFilter.java:50)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1767)
at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:583)
at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:143)
at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:548)
at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:226)
at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1180)
at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:513)
at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:185)
at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1112)
at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141)
at org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.java:119)
at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:134)
at org.eclipse.jetty.server.Server.handle(Server.java:539)
at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:333)
at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:251)
at org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:283)
at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:108)
at org.eclipse.jetty.io.SelectChannelEndPoint$2.run(SelectChannelEndPoint.java:93)
at org.eclipse.jetty.util.thread.strategy.ExecuteProduceConsume.executeProduceConsume(ExecuteProduceConsume.java:303)
at org.eclipse.jetty.util.thread.strategy.ExecuteProduceConsume.produceConsume(ExecuteProduceConsume.java:148)
at org.eclipse.jetty.util.thread.strategy.ExecuteProduceConsume.run(ExecuteProduceConsume.java:136)
at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:671)
at org.eclipse.jetty.util.thread.QueuedThreadPool$2.run(QueuedThreadPool.java:589)
at java.lang.Thread.run(Thread.java:748)