java.util.ConcurrentModificationException
   at java.util.AbstractList$Itr.checkForComodification(AbstractList.java:372)
   at java.util.AbstractList$Itr.next(AbstractList.java:343)
   at org.netbeans.modules.html.parser.ElementsFactory$CommonOpenTag.removeChildren(ElementsFactory.java:432)
   at org.netbeans.modules.html.parser.ParseTreeBuilder.appendChildrenToNewParent(ParseTreeBuilder.java:496)
   at org.netbeans.modules.html.parser.ParseTreeBuilder.appendChildrenToNewParent(ParseTreeBuilder.java:77)
   at nu.validator.htmlparser.impl.TreeBuilder.adoptionAgencyEndTag(TreeBuilder.java:4484)
   at nu.validator.htmlparser.impl.TreeBuilder.startTag(TreeBuilder.java:1936)
   at org.netbeans.modules.html.parser.ParseTreeBuilder.startTag(ParseTreeBuilder.java:388)
   at nu.validator.htmlparser.impl.Tokenizer.emitCurrentTagToken(Tokenizer.java:1136)
   at nu.validator.htmlparser.impl.Tokenizer.stateLoop(Tokenizer.java:2070)
   at nu.validator.htmlparser.impl.Tokenizer.tokenizeBuffer(Tokenizer.java:1331)
   at nu.validator.htmlparser.io.Driver.runStates(Driver.java:316)
   at nu.validator.htmlparser.io.Driver.tokenize(Driver.java:216)
   at org.netbeans.modules.html.parser.Html5Parser.parse(Html5Parser.java:134)
   at org.netbeans.modules.html.editor.lib.api.SyntaxAnalyzerResult.doParseHtml(SyntaxAnalyzerResult.java:245)
   at org.netbeans.modules.html.editor.lib.api.SyntaxAnalyzerResult.parseHtml(SyntaxAnalyzerResult.java:166)
   at org.netbeans.modules.html.editor.api.gsf.HtmlParserResult.root(HtmlParserResult.java:134)
   at org.netbeans.modules.html.editor.indexing.HtmlFileModel.init(HtmlFileModel.java:142)
   at org.netbeans.modules.html.editor.indexing.HtmlFileModel.<init>(HtmlFileModel.java:95)
   at org.netbeans.modules.html.editor.indexing.HtmlIndexer.index(HtmlIndexer.java:82)
   at org.netbeans.modules.parsing.spi.indexing.Indexable$MyAccessor$3.run(Indexable.java:216)
   at org.netbeans.modules.parsing.impl.indexing.RepositoryUpdater.runIndexer(RepositoryUpdater.java:258)
   at org.netbeans.modules.parsing.spi.indexing.Indexable$MyAccessor.index(Indexable.java:214)
   at org.netbeans.modules.parsing.impl.indexing.RepositoryUpdater$Work$3.run(RepositoryUpdater.java:2743)
   at org.netbeans.modules.parsing.impl.TaskProcessor.callUserTask(TaskProcessor.java:583)
   at org.netbeans.modules.parsing.api.ParserManager$UserTaskAction.run(ParserManager.java:150)
   at org.netbeans.modules.parsing.api.ParserManager$UserTaskAction.run(ParserManager.java:134)
   at org.netbeans.modules.parsing.impl.TaskProcessor$2.call(TaskProcessor.java:200)
   at org.netbeans.modules.parsing.impl.TaskProcessor$2.call(TaskProcessor.java:197)
   at org.netbeans.modules.masterfs.filebasedfs.utils.FileChangedManager.priorityIO(FileChangedManager.java:168)
   at org.netbeans.modules.masterfs.providers.ProvidedExtensions.priorityIO(ProvidedExtensions.java:360)
   at org.netbeans.modules.parsing.impl.Utilities.runPriorityIO(Utilities.java:72)
   at org.netbeans.modules.parsing.impl.TaskProcessor.runUserTask(TaskProcessor.java:197)
   at org.netbeans.modules.parsing.api.ParserManager.parse(ParserManager.java:102)
   at org.netbeans.modules.parsing.impl.indexing.RepositoryUpdater$Work.indexEmbedding(RepositoryUpdater.java:2699)
   at org.netbeans.modules.parsing.impl.indexing.RepositoryUpdater$Work.doIndex(RepositoryUpdater.java:2492)
   at org.netbeans.modules.parsing.impl.indexing.RepositoryUpdater$Work.access$1500(RepositoryUpdater.java:2015)
   at org.netbeans.modules.parsing.impl.indexing.RepositoryUpdater$Work$2.run(RepositoryUpdater.java:2304)
   at org.netbeans.modules.parsing.impl.indexing.RepositoryUpdater$Work$2.run(RepositoryUpdater.java:2302)
   at org.netbeans.modules.parsing.impl.indexing.errors.TaskCache.refreshTransaction(TaskCache.java:541)
   at org.netbeans.modules.parsing.impl.indexing.RepositoryUpdater$Work.index(RepositoryUpdater.java:2302)
   at org.netbeans.modules.parsing.impl.indexing.RepositoryUpdater$AbstractRootsWork.scanSource(RepositoryUpdater.java:4692)
   at org.netbeans.modules.parsing.impl.indexing.RepositoryUpdater$AbstractRootsWork.scanSources(RepositoryUpdater.java:4422)
   at org.netbeans.modules.parsing.impl.indexing.RepositoryUpdater$RootsWork.getDone(RepositoryUpdater.java:4135)
   at org.netbeans.modules.parsing.impl.indexing.RepositoryUpdater$Work.doTheWork(RepositoryUpdater.java:2883)
   at org.netbeans.modules.parsing.impl.indexing.RepositoryUpdater$Task._run(RepositoryUpdater.java:5103)
   at org.netbeans.modules.parsing.impl.indexing.RepositoryUpdater$Task.access$4800(RepositoryUpdater.java:4796)
   at org.netbeans.modules.parsing.impl.indexing.RepositoryUpdater$Task$2$1.run(RepositoryUpdater.java:5040)
   at org.netbeans.modules.parsing.impl.RunWhenScanFinishedSupport.performScan(RunWhenScanFinishedSupport.java:90)
   at org.netbeans.modules.parsing.impl.indexing.RepositoryUpdater$Task$2.call(RepositoryUpdater.java:5036)
   at org.netbeans.modules.parsing.impl.indexing.RepositoryUpdater$Task$2.call(RepositoryUpdater.java:5032)
   at org.netbeans.modules.masterfs.filebasedfs.utils.FileChangedManager.priorityIO(FileChangedManager.java:168)
   at org.netbeans.modules.masterfs.providers.ProvidedExtensions.priorityIO(ProvidedExtensions.java:360)
   at org.netbeans.modules.parsing.impl.Utilities.runPriorityIO(Utilities.java:72)
   at org.netbeans.modules.parsing.impl.indexing.RepositoryUpdater$Task.run(RepositoryUpdater.java:5032)
   at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:441)
   at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
   at java.util.concurrent.FutureTask.run(FutureTask.java:138)
   at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1452)
   at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:2032)