Reproduced by:
1. configure IM Plugin on Adminstrator Page (/admin/plugins/impresence2/gtalk/config.action)
2, plugin code in a confluence page:

3. Result

NPE is visible in UI: "Error formatting macro: im: java.lang.NullPointerException"

logfile

2007-07-30 11:15:07,939 ERROR [http-8080-1] [renderer.v2.components.MacroRendererComponent] processMacro Unexpected error formatting macro: im
..
java.lang.NullPointerException
at com.atlassian.confluence.extra.impresence2.GtalkPresenceReporter.getPresenceXHTML(GtalkPresenceReporter.java:93)
at com.atlassian.confluence.extra.impresence2.AbstractPresenceMacro.execute(AbstractPresenceMacro.java:73)
at com.atlassian.renderer.v2.macro.ResourceAwareMacroDecorator.execute(ResourceAwareMacroDecorator.java:45)
at com.atlassian.renderer.v2.components.MacroRendererComponent.processMacro(MacroRendererComponent.java:340)
at com.atlassian.renderer.v2.components.MacroRendererComponent.makeMacro(MacroRendererComponent.java:241)
at com.atlassian.renderer.v2.components.MacroRendererComponent.makeMacro(MacroRendererComponent.java:130)
at com.atlassian.renderer.v2.components.MacroRendererComponent.handlePotentialMacro(MacroRendererComponent.java:115)
at com.atlassian.renderer.v2.components.MacroRendererComponent.render(MacroRendererComponent.java:77)
at com.atlassian.renderer.v2.V2Renderer.render(V2Renderer.java:54)
at com.atlassian.renderer.v2.V2RendererFacade.convertWikiToXHtml(V2RendererFacade.java:57)
at sun.reflect.GeneratedMethodAccessor290.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
..