Errors in the wiki console when exporting a page as HTML

2023-11-16 17:48:12,810 [qtp382750013-186 - http://localhost:8080/xwiki/bin/export/Sandbox/WebHome?format=html] ERROR o.x.l.i.c.DefaultLESSCompiler  - Error during the compilation of the resource [org.xwiki.lesscss.internal.resources.LESSObjectPropertyResourceReference@dd996b66].
org.xwiki.lesscss.compiler.LESSCompilerException: Failed to compile the resource [org.xwiki.lesscss.internal.resources.LESSObjectPropertyResourceReference@dd996b66] with LESS.
        at org.xwiki.lesscss.internal.compiler.CachedLESSCompiler.compute(CachedLESSCompiler.java:136)
        at org.xwiki.lesscss.internal.compiler.CachedLESSCompiler.compute(CachedLESSCompiler.java:54)
        at org.xwiki.lesscss.internal.cache.AbstractCachedCompiler.getResult(AbstractCachedCompiler.java:137)
        at org.xwiki.lesscss.internal.cache.AbstractCachedCompiler.getResult(AbstractCachedCompiler.java:85)
        at org.xwiki.lesscss.internal.compiler.DefaultLESSCompiler.compile(DefaultLESSCompiler.java:66)
        at com.xpn.xwiki.web.sx.SxDocumentSource.getContent(SxDocumentSource.java:141)
        at org.xwiki.skinx.internal.AbstractSxExportURLFactoryActionHandler.getContent(AbstractSxExportURLFactoryActionHandler.java:168)
        at org.xwiki.skinx.internal.AbstractSxExportURLFactoryActionHandler.processSx(AbstractSxExportURLFactoryActionHandler.java:127)
        at org.xwiki.skinx.internal.AbstractSxExportURLFactoryActionHandler.createURL(AbstractSxExportURLFactoryActionHandler.java:103)
        at com.xpn.xwiki.web.ExportURLFactory.createURL(ExportURLFactory.java:461)
        at com.xpn.xwiki.XWiki.getURL(XWiki.java:5536)
        at com.xpn.xwiki.plugin.skinx.AbstractDocumentSkinExtensionPlugin.getDocumentSkinExtensionURL(AbstractDocumentSkinExtensionPlugin.java:522)
        at com.xpn.xwiki.plugin.skinx.CssSkinExtensionPlugin.getLink(CssSkinExtensionPlugin.java:88)
        at com.xpn.xwiki.plugin.skinx.AbstractSkinExtensionPlugin.getImportString(AbstractSkinExtensionPlugin.java:344)
        at com.xpn.xwiki.plugin.skinx.AbstractSkinExtensionPlugin.endParsing(AbstractSkinExtensionPlugin.java:445)
        at com.xpn.xwiki.plugin.skinx.AbstractDocumentSkinExtensionPlugin.endParsing(AbstractDocumentSkinExtensionPlugin.java:336)
        at com.xpn.xwiki.plugin.skinx.CssSkinExtensionPlugin.endParsing(CssSkinExtensionPlugin.java:116)
        at com.xpn.xwiki.plugin.XWikiPluginManager.endParsing(XWikiPluginManager.java:272)
        at com.xpn.xwiki.export.html.HtmlPackager.evaluateDocumentContent(HtmlPackager.java:278)
        at com.xpn.xwiki.export.html.HtmlPackager.renderDocument(HtmlPackager.java:247)
        at com.xpn.xwiki.export.html.HtmlPackager.renderDocuments(HtmlPackager.java:301)
        at com.xpn.xwiki.export.html.HtmlPackager.export(HtmlPackager.java:384)
        at com.xpn.xwiki.web.ExportAction.exportHTML(ExportAction.java:148)
        at com.xpn.xwiki.web.ExportAction.render(ExportAction.java:95)
        at com.xpn.xwiki.web.XWikiAction.execute(XWikiAction.java:637)
        at com.xpn.xwiki.web.XWikiAction.execute(XWikiAction.java:339)
        at com.xpn.xwiki.web.LegacyActionServlet.service(LegacyActionServlet.java:114)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:590)
        at org.eclipse.jetty.servlet.ServletHolder$NotAsync.service(ServletHolder.java:1419)
        at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:764)
        at org.eclipse.jetty.servlet.ServletHandler$ChainEnd.doFilter(ServletHandler.java:1624)
        at com.xpn.xwiki.web.ActionFilter.doFilter(ActionFilter.java:122)
        at org.eclipse.jetty.servlet.FilterHolder.doFilter(FilterHolder.java:202)
        at org.eclipse.jetty.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1594)
        at org.xwiki.wysiwyg.filter.ConversionFilter.doFilter(ConversionFilter.java:61)
        at org.eclipse.jetty.servlet.FilterHolder.doFilter(FilterHolder.java:202)
        at org.eclipse.jetty.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1594)
        at org.xwiki.container.servlet.filters.internal.SetHTTPHeaderFilter.doFilter(SetHTTPHeaderFilter.java:63)
        at org.eclipse.jetty.servlet.FilterHolder.doFilter(FilterHolder.java:202)
        at org.eclipse.jetty.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1594)
        at org.xwiki.resource.servlet.RoutingFilter.doFilter(RoutingFilter.java:132)
        at org.eclipse.jetty.servlet.FilterHolder.doFilter(FilterHolder.java:202)
        at org.eclipse.jetty.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1594)
        at org.xwiki.container.servlet.filters.internal.SavedRequestRestorerFilter.doFilter(SavedRequestRestorerFilter.java:208)
        at org.eclipse.jetty.servlet.FilterHolder.doFilter(FilterHolder.java:202)
        at org.eclipse.jetty.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1594)
        at org.xwiki.container.servlet.filters.internal.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:111)
        at org.eclipse.jetty.servlet.FilterHolder.doFilter(FilterHolder.java:210)
        at org.eclipse.jetty.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1594)
        at org.eclipse.jetty.websocket.servlet.WebSocketUpgradeFilter.doFilter(WebSocketUpgradeFilter.java:164)
        at org.eclipse.jetty.servlet.FilterHolder.doFilter(FilterHolder.java:202)
        at org.eclipse.jetty.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1594)
        at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:506)
        at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:131)
        at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:578)
        at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:122)
        at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:223)
        at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:1571)
        at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:221)
        at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1378)
        at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:176)
        at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:463)
        at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:1544)
        at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:174)
        at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1300)
        at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:129)
        at org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:192)
        at org.eclipse.jetty.server.handler.HandlerList.handle(HandlerList.java:51)
        at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:122)
        at org.eclipse.jetty.server.Server.handle(Server.java:562)
        at org.eclipse.jetty.server.HttpChannel.lambda$handle$0(HttpChannel.java:418)
        at org.eclipse.jetty.server.HttpChannel.dispatch(HttpChannel.java:675)
        at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:410)
        at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:282)
        at org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:319)
        at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:100)
        at org.eclipse.jetty.io.SocketChannelEndPoint$1.run(SocketChannelEndPoint.java:101)
        at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:894)
        at org.eclipse.jetty.util.thread.QueuedThreadPool$Runner.run(QueuedThreadPool.java:1038)
        at java.base/java.lang.Thread.run(Thread.java:834)
Caused by: com.github.sommeri.less4j.Less4jException: Could not compile less. 12 error(s) occurred:
ERROR 43:3 no viable alternative at input 'background-image' in ruleset (which started at 42:1)
 42: .notifications-toggles .bootstrap-switch .bootstrap-switch-label {
 43:   background-image: linear-gradient(, #f8f8f8 50%);
 44:   color: #4d5860;ERROR 43:3 no viable alternative at input 'background-image' in ruleset (which started at 43:3)
 42: .notifications-toggles .bootstrap-switch .bootstrap-switch-label {
 43:   background-image: linear-gradient(, #f8f8f8 50%);
 44:   color: #4d5860;...        at com.github.sommeri.less4j.core.ThreadUnsafeLessCompiler.toAntlrTree(ThreadUnsafeLessCompiler.java:136)
        at com.github.sommeri.less4j.core.ThreadUnsafeLessCompiler.doCompile(ThreadUnsafeLessCompiler.java:101)
        at com.github.sommeri.less4j.core.ThreadUnsafeLessCompiler.compile(ThreadUnsafeLessCompiler.java:85)
        at com.github.sommeri.less4j.core.DefaultLessCompiler.compile(DefaultLessCompiler.java:56)
        at org.xwiki.lesscss.internal.compiler.less4j.Less4jCompiler.compile(Less4jCompiler.java:67)
        at org.xwiki.lesscss.internal.compiler.CachedLESSCompiler.compute(CachedLESSCompiler.java:125)
        ... 79 common frames omitted