NPE if facet query hits timeout or exception

java.lang.NullPointerException
	at org.apache.solr.handler.component.FacetComponent.refineFacets(FacetComponent.java:990)
	at org.apache.solr.handler.component.FacetComponent.handleResponses(FacetComponent.java:699)
	at org.apache.solr.handler.component.SearchHandler.handleRequestBody(SearchHandler.java:488)
	at org.apache.solr.handler.RequestHandlerBase.handleRequest(RequestHandlerBase.java:216)
	at org.apache.solr.core.SolrCore.execute(SolrCore.java:2646)
	at org.apache.solr.servlet.HttpSolrCall.execute(HttpSolrCall.java:794)
	at org.apache.solr.servlet.HttpSolrCall.call(HttpSolrCall.java:567)
	at org.apache.solr.servlet.SolrDispatchFilter.doFilter(SolrDispatchFilter.java:427)
	at org.apache.solr.servlet.SolrDispatchFilter.doFilter(SolrDispatchFilter.java:357)
	at org.eclipse.jetty.servlet.FilterHolder.doFilter(FilterHolder.java:201)
	at org.eclipse.jetty.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1601)
	at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:548)
	at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:143)
	at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:602)
	at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:127)
	at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:235)
	at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:1612)
	at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:233)
	at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1434)
	at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:188)
	at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:501)
	at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:1582)
	at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:186)
	at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1349)
	at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141)
	at org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:191)
	at org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.java:146)
	at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:127)
	at org.eclipse.jetty.rewrite.handler.RewriteHandler.handle(RewriteHandler.java:322)
	at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:127)
	at org.eclipse.jetty.server.Server.handle(Server.java:516)
	at org.eclipse.jetty.server.HttpChannel.lambda$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:105)
	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:773)
	at org.eclipse.jetty.util.thread.QueuedThreadPool$Runner.run(QueuedThreadPool.java:905)
	at java.base/java.lang.Thread.run(Unknown Source)