Null Pointer Exception in Blogger

When publishing my previous post, Blogger gives me the infamous null pointer exception:

HTTP Status 500 -

---

type Exception report

message

description The server encountered an internal error () that prevented it from fulfilling this request.

exception

org.apache.jasper.JasperException
	at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:254)
	at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:295)
	at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:241)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:247)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:256)
	at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
	at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
	at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
	at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:494)
	at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)
	at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
	at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
	at org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2415)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:180)
	at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
	at org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.java:171)
	at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:172)
	at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)
	at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
	at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:174)
	at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
	at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
	at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
	at org.apache.coyote.tomcat4.CoyoteAdapter.service(CoyoteAdapter.java:223)
	at org.apache.jk.server.JkCoyoteHandler.invoke(JkCoyoteHandler.java:261)
	at org.apache.jk.common.HandlerRequest.invoke(HandlerRequest.java:360)
	at org.apache.jk.common.ChannelSocket.invoke(ChannelSocket.java:604)
	at org.apache.jk.common.ChannelSocket.processConnection(ChannelSocket.java:562)
	at org.apache.jk.common.SocketConnection.runIt(ChannelSocket.java:679)
	at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:619)
	at java.lang.Thread.run(Thread.java:534)

root cause

java.lang.NullPointerException
	at com.pyra.blogger.PostCache.setPostFilename(PostCache.java:1162)
	at com.pyra.blogger.Post.assignFilename(Post.java:448)
	at com.pyra.utils.Archiver.assignPostFilename(Archiver.java:406)
	at com.pyra.blogger.Blog.addPost(Blog.java:626)
	at org.apache.jsp.PostEdit_0002daction_pyra._jspService(PostEdit_0002daction_pyra.java:726)
	at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:137)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
	at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:210)
	at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:295)
	at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:241)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:247)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:256)
	at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
	at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
	at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
	at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:494)
	at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)
	at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
	at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
	at org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2415)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:180)
	at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
	at org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.java:171)
	at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:172)
	at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)
	at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
	at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:174)
	at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
	at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
	at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
	at org.apache.coyote.tomcat4.CoyoteAdapter.service(CoyoteAdapter.java:223)
	at org.apache.jk.server.JkCoyoteHandler.invoke(JkCoyoteHandler.java:261)
	at org.apache.jk.common.HandlerRequest.invoke(HandlerRequest.java:360)
	at org.apache.jk.common.ChannelSocket.invoke(ChannelSocket.java:604)
	at org.apache.jk.common.ChannelSocket.processConnection(ChannelSocket.java:562)
	at org.apache.jk.common.SocketConnection.runIt(ChannelSocket.java:679)
	at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:619)
	at java.lang.Thread.run(Thread.java:534)

---

Apache Tomcat/4.1.24