org.xwiki.rendering.RenderingException: Failed to execute renderer
 at org.xwiki.rendering.async.internal.DefaultAsyncRendererExecutor.syncRender(DefaultAsyncRendererExecutor.java:287)
 at org.xwiki.rendering.async.internal.DefaultAsyncRendererExecutor.render(DefaultAsyncRendererExecutor.java:267)
 at org.xwiki.rendering.async.internal.block.DefaultBlockAsyncRendererExecutor.render(DefaultBlockAsyncRendererExecutor.java:154)
 at com.xpn.xwiki.internal.template.InternalTemplateManager.render(InternalTemplateManager.java:904)
 at com.xpn.xwiki.internal.template.InternalTemplateManager.renderFromSkin(InternalTemplateManager.java:866)
 at com.xpn.xwiki.internal.template.InternalTemplateManager.render(InternalTemplateManager.java:853)
 at com.xpn.xwiki.internal.template.InternalTemplateManager.renderNoException(InternalTemplateManager.java:808)
 at com.xpn.xwiki.internal.template.InternalTemplateManager.renderNoException(InternalTemplateManager.java:800)
 at com.xpn.xwiki.internal.template.DefaultTemplateManager.renderNoException(DefaultTemplateManager.java:79)
 at com.xpn.xwiki.internal.template.DefaultTemplateManager.renderNoException(DefaultTemplateManager.java:73)
 at org.xwiki.template.script.TemplateScriptService.render(TemplateScriptService.java:54)
 at jdk.internal.reflect.GeneratedMethodAccessor185.invoke(Unknown Source)
 at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
 at java.base/java.lang.reflect.Method.invoke(Method.java:569)
 at org.apache.velocity.util.introspection.UberspectImpl$VelMethodImpl.doInvoke(UberspectImpl.java:571)
 at org.apache.velocity.util.introspection.UberspectImpl$VelMethodImpl.invoke(UberspectImpl.java:554)
 at org.apache.velocity.runtime.parser.node.ASTMethod.execute(ASTMethod.java:221)
 at org.apache.velocity.runtime.parser.node.ASTReference.execute(ASTReference.java:368)
 at org.apache.velocity.runtime.parser.node.ASTReference.render(ASTReference.java:492)
 at org.apache.velocity.runtime.parser.node.ASTBlock.render(ASTBlock.java:147)
 at org.apache.velocity.runtime.directive.VelocimacroProxy.render(VelocimacroProxy.java:218)
 at org.apache.velocity.runtime.directive.RuntimeMacro.render(RuntimeMacro.java:331)
 at org.apache.velocity.runtime.directive.RuntimeMacro.render(RuntimeMacro.java:261)
 at org.apache.velocity.runtime.parser.node.ASTDirective.render(ASTDirective.java:304)
 at org.apache.velocity.runtime.parser.node.ASTBlock.render(ASTBlock.java:147)
 at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:439)
 at org.apache.velocity.runtime.parser.node.ASTIfStatement.render(ASTIfStatement.java:190)
 at org.apache.velocity.runtime.parser.node.ASTBlock.render(ASTBlock.java:147)
 at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:439)
 at org.apache.velocity.runtime.parser.node.ASTIfStatement.render(ASTIfStatement.java:190)
 at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:439)
 at org.apache.velocity.Template.merge(Template.java:358)
 at org.apache.velocity.Template.merge(Template.java:262)
 at org.xwiki.velocity.internal.InternalVelocityEngine.evaluate(InternalVelocityEngine.java:225)
 at com.xpn.xwiki.internal.template.VelocityTemplateEvaluator.evaluateContent(VelocityTemplateEvaluator.java:105)
 at com.xpn.xwiki.internal.template.TemplateAsyncRenderer.evaluateContent(TemplateAsyncRenderer.java:219)
 at com.xpn.xwiki.internal.template.TemplateAsyncRenderer.renderVelocity(TemplateAsyncRenderer.java:174)
 at com.xpn.xwiki.internal.template.TemplateAsyncRenderer.render(TemplateAsyncRenderer.java:135)
 at com.xpn.xwiki.internal.template.TemplateAsyncRenderer.render(TemplateAsyncRenderer.java:54)
 at org.xwiki.rendering.async.internal.DefaultAsyncRendererExecutor.lambda$syncRender$0(DefaultAsyncRendererExecutor.java:284)
 at com.xpn.xwiki.internal.security.authorization.DefaultAuthorExecutor.call(DefaultAuthorExecutor.java:98)
 at org.xwiki.rendering.async.internal.DefaultAsyncRendererExecutor.syncRender(DefaultAsyncRendererExecutor.java:284)
 at org.xwiki.rendering.async.internal.DefaultAsyncRendererExecutor.render(DefaultAsyncRendererExecutor.java:267)
 at org.xwiki.rendering.async.internal.block.DefaultBlockAsyncRendererExecutor.render(DefaultBlockAsyncRendererExecutor.java:154)
 at com.xpn.xwiki.internal.template.InternalTemplateManager.render(InternalTemplateManager.java:904)
 at com.xpn.xwiki.internal.template.InternalTemplateManager.renderFromSkin(InternalTemplateManager.java:866)
 at com.xpn.xwiki.internal.template.InternalTemplateManager.renderFromSkin(InternalTemplateManager.java:846)
 at com.xpn.xwiki.internal.template.InternalTemplateManager.render(InternalTemplateManager.java:832)
 at com.xpn.xwiki.internal.template.DefaultTemplateManager.render(DefaultTemplateManager.java:91)
 at com.xpn.xwiki.internal.template.DefaultTemplateManager.render(DefaultTemplateManager.java:85)
 at com.xpn.xwiki.XWiki.evaluateTemplate(XWiki.java:2565)
 at com.xpn.xwiki.web.Utils.parseTemplate(Utils.java:180)
 at com.xpn.xwiki.web.XWikiAction.execute(XWikiAction.java:651)
 at com.xpn.xwiki.web.XWikiAction.execute(XWikiAction.java:339)
 at com.xpn.xwiki.web.LegacyActionServlet.service(LegacyActionServlet.java:108)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
 at com.xpn.xwiki.web.ActionFilter.doFilter(ActionFilter.java:122)
 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
 at org.xwiki.wysiwyg.filter.ConversionFilter.doFilter(ConversionFilter.java:61)
 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
 at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
 at org.xwiki.container.servlet.filters.internal.SetHTTPHeaderFilter.doFilter(SetHTTPHeaderFilter.java:63)
 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
 at org.xwiki.resource.servlet.RoutingFilter.doFilter(RoutingFilter.java:132)
 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
 at org.xwiki.container.servlet.filters.internal.SavedRequestRestorerFilter.doFilter(SavedRequestRestorerFilter.java:208)
 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
 at org.xwiki.container.servlet.filters.internal.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:111)
 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
 at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202)
 at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
 at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:541)
 at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139)
 at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
 at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:688)
 at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74)
 at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:351)
 at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:375)
 at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
 at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868)
 at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1594)
 at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
 at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
 at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
 at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
 at java.base/java.lang.Thread.run(Thread.java:840)
Caused by: org.xwiki.rendering.RenderingException: Failed to evaluate template with id [environment:/skins/flamingo/code.vm]
 at com.xpn.xwiki.internal.template.TemplateAsyncRenderer.evaluateContent(TemplateAsyncRenderer.java:221)
 at com.xpn.xwiki.internal.template.TemplateAsyncRenderer.renderVelocity(TemplateAsyncRenderer.java:174)
 at com.xpn.xwiki.internal.template.TemplateAsyncRenderer.render(TemplateAsyncRenderer.java:135)
 at com.xpn.xwiki.internal.template.TemplateAsyncRenderer.render(TemplateAsyncRenderer.java:54)
 at org.xwiki.rendering.async.internal.DefaultAsyncRendererExecutor.lambda$syncRender$0(DefaultAsyncRendererExecutor.java:284)
 at com.xpn.xwiki.internal.security.authorization.DefaultAuthorExecutor.call(DefaultAuthorExecutor.java:98)
 at org.xwiki.rendering.async.internal.DefaultAsyncRendererExecutor.syncRender(DefaultAsyncRendererExecutor.java:284)
 ... 95 more
Caused by: org.xwiki.velocity.XWikiVelocityException: Failed to evaluate content with namespace [environment:/skins/flamingo/view.vm]
 at org.xwiki.velocity.internal.InternalVelocityEngine.evaluate(InternalVelocityEngine.java:227)
 at com.xpn.xwiki.internal.template.VelocityTemplateEvaluator.evaluateContent(VelocityTemplateEvaluator.java:105)
 at com.xpn.xwiki.internal.template.TemplateAsyncRenderer.evaluateContent(TemplateAsyncRenderer.java:219)
 ... 101 more
Caused by: org.apache.velocity.exception.MethodInvocationException: Invocation of method 'getVersion' in  class com.xpn.xwiki.api.RevisionInfo threw exception java.lang.NullPointerException at environment:/skins/flamingo/code.vm[line 83, column 41]
 at org.apache.velocity.runtime.parser.node.ASTIdentifier.execute(ASTIdentifier.java:246)
 at org.apache.velocity.runtime.parser.node.ASTReference.execute(ASTReference.java:368)
 at org.apache.velocity.runtime.parser.node.ASTReference.value(ASTReference.java:704)
 at org.apache.velocity.runtime.parser.node.ASTExpression.value(ASTExpression.java:75)
 at org.apache.velocity.runtime.parser.node.ASTSetDirective.render(ASTSetDirective.java:242)
 at org.apache.velocity.runtime.parser.node.ASTBlock.render(ASTBlock.java:147)
 at org.apache.velocity.runtime.parser.node.ASTIfStatement.render(ASTIfStatement.java:171)
 at org.apache.velocity.runtime.parser.node.ASTBlock.render(ASTBlock.java:147)
 at org.apache.velocity.runtime.directive.Foreach.renderBlock(Foreach.java:309)
 at org.apache.velocity.runtime.directive.Foreach.render(Foreach.java:279)
 at org.apache.velocity.runtime.parser.node.ASTDirective.render(ASTDirective.java:304)
 at org.apache.velocity.runtime.parser.node.ASTBlock.render(ASTBlock.java:147)
 at org.apache.velocity.runtime.parser.node.ASTIfStatement.render(ASTIfStatement.java:171)
 at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:439)
 at org.apache.velocity.Template.merge(Template.java:358)
 at org.apache.velocity.Template.merge(Template.java:262)
 at org.xwiki.velocity.internal.InternalVelocityEngine.evaluate(InternalVelocityEngine.java:225)
 ... 103 more
Caused by: java.lang.NullPointerException