java.lang.NullPointerException: Netbeans documents must have 'mimeType' property: class javax.swing.text.html.HTMLDocument@12b9ce0
   at org.netbeans.modules.parsing.api.Source.create(Source.java:173)
   at org.netbeans.modules.parsing.impl.indexing.RepositoryUpdater$Work.getActiveSource(RepositoryUpdater.java:2241)
   at org.netbeans.modules.parsing.impl.indexing.RepositoryUpdater$FileListWork.shouldRefresh(RepositoryUpdater.java:2359)
   at org.netbeans.modules.parsing.impl.indexing.RepositoryUpdater$FileListWork.invalidateSources(RepositoryUpdater.java:2350)
   at org.netbeans.modules.parsing.impl.indexing.RepositoryUpdater$Work.scanFiles(RepositoryUpdater.java:2106)
   at org.netbeans.modules.parsing.impl.indexing.RepositoryUpdater$FileListWork.getDone(RepositoryUpdater.java:2299)
   at org.netbeans.modules.parsing.impl.indexing.RepositoryUpdater$Work.doTheWork(RepositoryUpdater.java:2159)
   at org.netbeans.modules.parsing.impl.indexing.RepositoryUpdater$Task._run(RepositoryUpdater.java:3830)
   at org.netbeans.modules.parsing.impl.indexing.RepositoryUpdater$Task.run(RepositoryUpdater.java:3769)
   at org.netbeans.modules.parsing.impl.TaskProcessor$CompilationJob.run(TaskProcessor.java:610)
   at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:0)
   at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:0)
   at java.util.concurrent.FutureTask.run(FutureTask.java:0)
   at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:0)
   at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:0)
   at java.lang.Thread.run(Thread.java:0)