NPE occured when redirection to a non-icemobile page which did not have mobi:deviceResource present. the null value should be detected and a theme not loaded instead:-

SEVERE: Error Rendering View[/xhtml/error.xhtml]
java.lang.NullPointerException
        at org.icemobile.util.CSSUtils.getThemeCSSFileName(CSSUtils.java:150)
        at org.icefaces.mobi.component.deviceresource.DeviceResourceRenderer$AddTheme.processEvent(DeviceResourceRenderer.jav
a:382)
        at javax.faces.event.SystemEvent.processListener(SystemEvent.java:106)
        at com.sun.faces.application.ApplicationImpl.processListeners(ApplicationImpl.java:2163)
        at com.sun.faces.application.ApplicationImpl.invokeListenersFor(ApplicationImpl.java:2139)
        at com.sun.faces.application.ApplicationImpl.publishEvent(ApplicationImpl.java:303)
        at com.sun.faces.application.ApplicationImpl.publishEvent(ApplicationImpl.java:247)
        at javax.faces.component.UIComponentBase.encodeBegin(UIComponentBase.java:818)
        at javax.faces.component.UIViewRoot.encodeBegin(UIViewRoot.java:954)
        at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1777)
        at com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:439)
        at com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:124)
        at javax.faces.application.ViewHandlerWrapper.renderView(ViewHandlerWrapper.java:286)
        at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:120)
        at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
        at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:139)
        at javax.faces.webapp.FacesServlet.service(FacesServlet.java:594)
        at weblogic.servlet.internal.StubSecurityHelper$ServletServiceAction.run(StubSecurityHelper.java:227)
        at weblogic.servlet.internal.StubSecurityHelper.invokeServlet(StubSecurityHelper.java:125)
        at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:300)
        at weblogic.servlet.internal.TailFilter.doFilter(TailFilter.java:26)
        at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:56)
        at com.icesoft.servlet.MultipartFilter.doFilter(MultipartFilter.java:74)
        at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:56)
        at weblogic.servlet.internal.RequestEventsFilter.doFilter(RequestEventsFilter.java:27)
        at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:56)
        at weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.wrapRun(WebAppServletContext.java:3715)
        at weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.run(WebAppServletContext.java:3681)
        at weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:321)
        at weblogic.security.service.SecurityManager.runAs(SecurityManager.java:120)
        at weblogic.servlet.internal.WebAppServletContext.securedExecute(WebAppServletContext.java:2277)
        at weblogic.servlet.internal.WebAppServletContext.execute(WebAppServletContext.java:2183)
        at weblogic.servlet.internal.ServletRequestImpl.run(ServletRequestImpl.java:1454)
        at weblogic.work.ExecuteThread.execute(ExecuteThread.java:209)
        at weblogic.work.ExecuteThread.run(ExecuteThread.java:178)