NullPointerException when importing a XAR

2020-06-24 17:37:21,967 [qtp1112280004-81 - http://localhost:8080/xwiki/bin/get/XWiki/XWikiPreferences?xpage=packagedescriptor&package=missing.xar] ERROR c.x.x.XWiki                    - Error while evaluating velocity template [packagedescriptor.vm] 
org.xwiki.rendering.RenderingException: Failed to execute renderer
	at org.xwiki.rendering.async.internal.DefaultAsyncRendererExecutor.syncRender(DefaultAsyncRendererExecutor.java:270)
	at org.xwiki.rendering.async.internal.DefaultAsyncRendererExecutor.render(DefaultAsyncRendererExecutor.java:250)
	at org.xwiki.rendering.async.internal.block.DefaultBlockAsyncRendererExecutor.render(DefaultBlockAsyncRendererExecutor.java:154)
	at com.xpn.xwiki.internal.template.InternalTemplateManager.render(InternalTemplateManager.java:772)
	at com.xpn.xwiki.internal.template.InternalTemplateManager.renderFromSkin(InternalTemplateManager.java:745)
	at com.xpn.xwiki.internal.template.InternalTemplateManager.renderFromSkin(InternalTemplateManager.java:725)
	at com.xpn.xwiki.internal.template.InternalTemplateManager.render(InternalTemplateManager.java:711)
	at com.xpn.xwiki.internal.template.DefaultTemplateManager.render(DefaultTemplateManager.java:78)
	at com.xpn.xwiki.XWiki.evaluateTemplate(XWiki.java:2505)
	at com.xpn.xwiki.web.Utils.parseTemplate(Utils.java:179)
	at com.xpn.xwiki.web.XWikiAction.execute(XWikiAction.java:576)
	at com.xpn.xwiki.web.XWikiAction.execute(XWikiAction.java:250)
	at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:425)
	at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:228)
	at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1913)
	at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:462)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:707)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
	at org.eclipse.jetty.servlet.ServletHolder$NotAsyncServlet.service(ServletHolder.java:1411)
	at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:763)
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1631)
	at com.xpn.xwiki.web.ActionFilter.doFilter(ActionFilter.java:122)
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1618)
	at org.xwiki.wysiwyg.filter.ConversionFilter.doFilter(ConversionFilter.java:109)
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1618)
	at org.xwiki.container.servlet.filters.internal.SetHTTPHeaderFilter.doFilter(SetHTTPHeaderFilter.java:63)
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1618)
	at org.xwiki.container.servlet.filters.internal.SavedRequestRestorerFilter.doFilter(SavedRequestRestorerFilter.java:208)
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1618)
	at org.xwiki.container.servlet.filters.internal.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:111)
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1618)
	at org.xwiki.resource.servlet.RoutingFilter.doFilter(RoutingFilter.java:132)
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1610)
	at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:549)
	at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:143)
	at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:602)
	at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:127)
	at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:235)
	at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:1610)
	at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:233)
	at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1369)
	at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:188)
	at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:489)
	at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:1580)
	at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:186)
	at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1284)
	at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141)
	at org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:221)
	at org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.java:146)
	at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:127)
	at org.eclipse.jetty.server.Server.handle(Server.java:501)
	at org.eclipse.jetty.server.HttpChannel.lambda$handle$1(HttpChannel.java:383)
	at org.eclipse.jetty.server.HttpChannel.dispatch(HttpChannel.java:556)
	at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:375)
	at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:273)
	at org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:311)
	at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:103)
	at org.eclipse.jetty.io.ChannelEndPoint$1.run(ChannelEndPoint.java:104)
	at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.runTask(EatWhatYouKill.java:336)
	at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.doProduce(EatWhatYouKill.java:313)
	at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.tryProduce(EatWhatYouKill.java:171)
	at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.run(EatWhatYouKill.java:129)
	at org.eclipse.jetty.util.thread.ReservedThreadExecutor$ReservedThread.run(ReservedThreadExecutor.java:375)
	at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:806)
	at org.eclipse.jetty.util.thread.QueuedThreadPool$Runner.run(QueuedThreadPool.java:938)
	at java.lang.Thread.run(Thread.java:748)
Caused by: org.xwiki.rendering.RenderingException: Failed to evaluate template with id [/templates/packagedescriptor.vm]
	at com.xpn.xwiki.internal.template.TemplateAsyncRenderer.evaluateContent(TemplateAsyncRenderer.java:219)
	at com.xpn.xwiki.internal.template.TemplateAsyncRenderer.renderVelocity(TemplateAsyncRenderer.java:180)
	at com.xpn.xwiki.internal.template.TemplateAsyncRenderer.render(TemplateAsyncRenderer.java:137)
	at com.xpn.xwiki.internal.template.TemplateAsyncRenderer.render(TemplateAsyncRenderer.java:53)
	at org.xwiki.rendering.async.internal.DefaultAsyncRendererExecutor.lambda$syncRender$0(DefaultAsyncRendererExecutor.java:267)
	at com.xpn.xwiki.internal.security.authorization.DefaultAuthorExecutor.call(DefaultAuthorExecutor.java:98)
	at org.xwiki.rendering.async.internal.DefaultAsyncRendererExecutor.syncRender(DefaultAsyncRendererExecutor.java:267)
	... 65 common frames omitted
Caused by: org.xwiki.velocity.XWikiVelocityException: Failed to evaluate content with namespace [/templates/packagedescriptor.vm]
	at org.xwiki.velocity.internal.DefaultVelocityEngine.evaluate(DefaultVelocityEngine.java:289)
	at com.xpn.xwiki.render.DefaultVelocityManager.evaluate(DefaultVelocityManager.java:316)
	at com.xpn.xwiki.internal.template.VelocityTemplateEvaluator.evaluateContent(VelocityTemplateEvaluator.java:95)
	at com.xpn.xwiki.internal.template.TemplateAsyncRenderer.evaluateContent(TemplateAsyncRenderer.java:217)
	... 71 common frames omitted
Caused by: org.apache.velocity.exception.MethodInvocationException: Invocation of method 'toTree' in  class org.xwiki.model.script.ModelScriptService threw exception java.lang.NullPointerException at /templates/packagedescriptor.vm[line 47, column 36]
	at org.apache.velocity.runtime.parser.node.ASTMethod.handleInvocationException(ASTMethod.java:306)
	at org.apache.velocity.runtime.parser.node.ASTMethod.execute(ASTMethod.java:233)
	at org.apache.velocity.runtime.parser.node.ASTReference.execute(ASTReference.java:369)
	at org.apache.velocity.runtime.parser.node.ASTReference.value(ASTReference.java:701)
	at org.apache.velocity.runtime.parser.node.ASTMap.value(ASTMap.java:82)
	at org.apache.velocity.runtime.parser.node.ASTExpression.value(ASTExpression.java:72)
	at org.apache.velocity.runtime.parser.node.ASTSetDirective.render(ASTSetDirective.java:240)
	at org.apache.velocity.runtime.parser.node.ASTBlock.render(ASTBlock.java:144)
	at org.apache.velocity.runtime.parser.node.ASTIfStatement.render(ASTIfStatement.java:172)
	at org.apache.velocity.runtime.parser.node.ASTBlock.render(ASTBlock.java:144)
	at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:423)
	at org.apache.velocity.runtime.parser.node.ASTIfStatement.render(ASTIfStatement.java:191)
	at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:423)
	at org.apache.velocity.Template.merge(Template.java:358)
	at org.apache.velocity.Template.merge(Template.java:262)
	at org.xwiki.velocity.internal.DefaultVelocityEngine.evaluate(DefaultVelocityEngine.java:281)
	... 74 common frames omitted
Caused by: java.lang.NullPointerException: null
	at org.xwiki.model.reference.EntityReferenceTree.<init>(EntityReferenceTree.java:65)
	at org.xwiki.model.reference.EntityReferenceTree.<init>(EntityReferenceTree.java:46)
	at org.xwiki.model.script.ModelScriptService.toTree(ModelScriptService.java:912)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.apache.velocity.util.introspection.UberspectImpl$VelMethodImpl.doInvoke(UberspectImpl.java:565)
	at org.apache.velocity.util.introspection.UberspectImpl$VelMethodImpl.invoke(UberspectImpl.java:548)
	at org.apache.velocity.runtime.parser.node.ASTMethod.execute(ASTMethod.java:219)
	... 88 common frames omitted