Replication:

1) Make sure you have at least two environment variables set in your rhq-agent-env.bat/.sh.
2) Go to a resource that has a Configuration of a list of maps (e.g. the RHQ Agent's new Environment Script service resource).
3) Edit the configuration
4) Delete the first environment variable map you see (the one at the top)
5) Now edit the new, topmost environment variable map.

As soon as you click the edit button in step 5, you get this:

java.lang.IndexOutOfBoundsException: Index: 1, Size: 1
	at java.util.ArrayList.RangeCheck(ArrayList.java:547)
	at java.util.ArrayList.get(ArrayList.java:322)
	at org.hibernate.collection.PersistentBag.get(PersistentBag.java:423)
	at org.rhq.core.gui.configuration.MapInListUIComponentTreeFactory.<init>(MapInListUIComponentTreeFactory.java:42)
	at org.rhq.core.gui.configuration.ConfigRenderer.addListMemberProperty(ConfigRenderer.java:159)
	at org.rhq.core.gui.configuration.ConfigRenderer.encodeBegin(ConfigRenderer.java:149)
	at javax.faces.component.UIComponentBase.encodeBegin(UIComponentBase.java:801)
	at javax.faces.component.UIComponent.encodeAll(UIComponent.java:934)
	at javax.faces.render.Renderer.encodeChildren(Renderer.java:148)
	at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:825)
	at javax.faces.component.UIComponent.encodeAll(UIComponent.java:936)
	at javax.faces.component.UIComponent.encodeAll(UIComponent.java:942)
	at com.sun.facelets.FaceletViewHandler.renderView(FaceletViewHandler.java:592)
	at org.ajax4jsf.application.ViewHandlerWrapper.renderView(ViewHandlerWrapper.java:108)
	at org.ajax4jsf.application.AjaxViewHandler.renderView(AjaxViewHandler.java:189)
	at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:110)
	at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:100)
	at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:139)
	at javax.faces.webapp.FacesServlet.service(FacesServlet.java:266)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
	at org.ajax4jsf.webapp.BaseXMLFilter.doXmlFilter(BaseXMLFilter.java:147)
	at org.ajax4jsf.webapp.BaseFilter.doFilter(BaseFilter.java:276)
	at org.ajax4jsf.Filter.doFilter(Filter.java:175)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
	at org.rhq.enterprise.gui.legacy.AuthenticationFilter.doFilter(AuthenticationFilter.java:129)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
	at org.rhq.enterprise.gui.common.upload.MultipartFilter.doFilter(MultipartFilter.java:63)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
	at org.rhq.helpers.rtfilter.filter.RtFilter.doFilter(RtFilter.java:116)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
	at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:230)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
	at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:179)
	at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:84)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:104)
	at org.jboss.web.tomcat.service.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:157)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:241)
	at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844)
	at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:580)
	at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
	at java.lang.Thread.run(Thread.java:619)