java.lang.AssertionError
   at com.sun.tools.javac.util.Assert.error(Assert.java:155)
   at com.sun.tools.javac.util.Assert.checkNonNull(Assert.java:62)
   at com.sun.tools.javac.code.Symtab.enterClass(Symtab.java:730)
   at com.sun.tools.javadoc.main.DocEnv.<init>(DocEnv.java:161)
   at org.netbeans.modules.java.source.JavadocEnv.<init>(JavadocEnv.java:103)
   at org.netbeans.modules.java.source.JavadocEnv.<init>(JavadocEnv.java:89)
   at org.netbeans.modules.java.source.JavadocEnv$1.make(JavadocEnv.java:94)
   at org.netbeans.modules.java.source.JavadocEnv$1.make(JavadocEnv.java:92)
   at com.sun.tools.javac.util.Context.get(Context.java:150)
   at com.sun.tools.javadoc.main.DocEnv.instance(DocEnv.java:81)
   at com.sun.tools.javadoc.main.JavadocMemberEnter.<init>(JavadocMemberEnter.java:64)
   at org.netbeans.lib.nbjavac.services.NBJavadocMemberEnter.<init>(NBJavadocMemberEnter.java:68)
   at org.netbeans.lib.nbjavac.services.NBJavadocMemberEnter$1.make(NBJavadocMemberEnter.java:59)
   at org.netbeans.lib.nbjavac.services.NBJavadocMemberEnter$1.make(NBJavadocMemberEnter.java:57)
   at com.sun.tools.javac.util.Context.get(Context.java:150)
   at com.sun.tools.javac.comp.MemberEnter.instance(MemberEnter.java:74)
   at com.sun.tools.javac.comp.TypeEnter.<init>(TypeEnter.java:125)
   at com.sun.tools.javac.comp.TypeEnter.instance(TypeEnter.java:117)
   at com.sun.tools.javac.comp.Enter.<init>(Enter.java:135)
   at com.sun.tools.javadoc.main.JavadocEnter.<init>(JavadocEnter.java:66)
   at org.netbeans.lib.nbjavac.services.NBJavadocEnter.<init>(NBJavadocEnter.java:76)
   at org.netbeans.lib.nbjavac.services.NBJavadocEnter$1.make(NBJavadocEnter.java:67)
   at org.netbeans.lib.nbjavac.services.NBJavadocEnter$1.make(NBJavadocEnter.java:65)
   at com.sun.tools.javac.util.Context.get(Context.java:150)
   at com.sun.tools.javac.comp.Enter.instance(Enter.java:122)
   at com.sun.tools.javac.comp.Check.<init>(Check.java:119)
   at com.sun.tools.javac.comp.Check.instance(Check.java:105)
   at com.sun.tools.javac.comp.DeferredAttr.<init>(DeferredAttr.java:111)
   at com.sun.tools.javac.comp.DeferredAttr.instance(DeferredAttr.java:103)
   at com.sun.tools.javac.comp.Resolve.<init>(Resolve.java:123)
   at org.netbeans.lib.nbjavac.services.NBResolve.<init>(NBResolve.java:73)
   at org.netbeans.lib.nbjavac.services.NBResolve$1.make(NBResolve.java:67)
   at org.netbeans.lib.nbjavac.services.NBResolve$1.make(NBResolve.java:65)
   at com.sun.tools.javac.util.Context.get(Context.java:150)
   at com.sun.tools.javac.comp.Resolve.instance(Resolve.java:158)
   at com.sun.tools.javac.comp.Attr.<init>(Attr.java:128)
   at org.netbeans.lib.nbjavac.services.NBAttr.<init>(NBAttr.java:63)
   at org.netbeans.lib.nbjavac.services.NBAttr$1.make(NBAttr.java:55)
   at org.netbeans.lib.nbjavac.services.NBAttr$1.make(NBAttr.java:53)
   at com.sun.tools.javac.util.Context.get(Context.java:150)
   at com.sun.tools.javac.comp.Attr.instance(Attr.java:116)
   at com.sun.tools.javac.comp.Annotate.<init>(Annotate.java:102)
   at com.sun.tools.javac.comp.Annotate.instance(Annotate.java:77)
   at com.sun.tools.javac.jvm.ClassReader.<init>(ClassReader.java:234)
   at org.netbeans.lib.nbjavac.services.NBClassReader.<init>(NBClassReader.java:73)
   at org.netbeans.lib.nbjavac.services.NBClassReader$1.make(NBClassReader.java:64)
   at org.netbeans.lib.nbjavac.services.NBClassReader$1.make(NBClassReader.java:62)
   at com.sun.tools.javac.util.Context.get(Context.java:150)
   at com.sun.tools.javac.jvm.ClassReader.instance(ClassReader.java:225)
   at com.sun.tools.javac.code.ClassFinder.<init>(ClassFinder.java:186)
   at com.sun.tools.javadoc.main.JavadocClassFinder.<init>(JavadocClassFinder.java:71)
   at com.sun.tools.javadoc.main.JavadocClassFinder.lambda$preRegister$0(JavadocClassFinder.java:60)
   at com.sun.tools.javac.util.Context.get(Context.java:150)
   at com.sun.tools.javac.code.ClassFinder.instance(ClassFinder.java:177)
   at com.sun.tools.javac.code.Symtab.<init>(Symtab.java:456)
   at com.sun.tools.javac.code.Symtab.instance(Symtab.java:88)
   at com.sun.tools.javac.code.Types.<init>(Types.java:112)
   at com.sun.tools.javac.code.Types.instance(Types.java:106)
   at org.netbeans.api.java.source.TypeMirrorHandle.resolve(TypeMirrorHandle.java:281)
   at org.netbeans.api.java.source.TypeMirrorHandle.resolve(TypeMirrorHandle.java:252)
   at org.netbeans.modules.javafx2.editor.completion.impl.IdReferenceCompleter.complete(IdReferenceCompleter.java:81)
   at org.netbeans.modules.javafx2.editor.FXMLCompletion2$Q$Task.run(FXMLCompletion2.java:210)
   at org.netbeans.modules.parsing.impl.TaskProcessor.callUserTask(TaskProcessor.java:609)
   at org.netbeans.modules.parsing.api.ParserManager$MimeTaskAction.run(ParserManager.java:380)
   at org.netbeans.modules.parsing.api.ParserManager$MimeTaskAction.run(ParserManager.java:363)
   at org.netbeans.modules.parsing.impl.TaskProcessor$2.call(TaskProcessor.java:204)
   at org.netbeans.modules.parsing.impl.TaskProcessor$2.call(TaskProcessor.java:201)
   at org.netbeans.modules.masterfs.filebasedfs.utils.FileChangedManager.priorityIO(FileChangedManager.java:176)
   at org.netbeans.modules.masterfs.providers.ProvidedExtensions.priorityIO(ProvidedExtensions.java:360)
   at org.netbeans.modules.parsing.nb.DataObjectEnvFactory.runPriorityIO(DataObjectEnvFactory.java:141)
   at org.netbeans.modules.parsing.impl.Utilities.runPriorityIO(Utilities.java:90)
   at org.netbeans.modules.parsing.impl.TaskProcessor.runUserTask(TaskProcessor.java:201)
   at org.netbeans.modules.parsing.api.ParserManager.parse(ParserManager.java:334)
   at org.netbeans.modules.javafx2.editor.FXMLCompletion2$Q$Task.run(FXMLCompletion2.java:182)
   at org.netbeans.modules.parsing.impl.TaskProcessor.callUserTask(TaskProcessor.java:609)
   at org.netbeans.modules.parsing.api.ParserManager$UserTaskAction.run(ParserManager.java:153)
   at org.netbeans.modules.parsing.api.ParserManager$UserTaskAction.run(ParserManager.java:137)
   at org.netbeans.modules.parsing.impl.TaskProcessor$2.call(TaskProcessor.java:204)
   at org.netbeans.modules.parsing.impl.TaskProcessor$2.call(TaskProcessor.java:201)
   at org.netbeans.modules.masterfs.filebasedfs.utils.FileChangedManager.priorityIO(FileChangedManager.java:176)
   at org.netbeans.modules.masterfs.providers.ProvidedExtensions.priorityIO(ProvidedExtensions.java:360)
   at org.netbeans.modules.parsing.nb.DataObjectEnvFactory.runPriorityIO(DataObjectEnvFactory.java:141)
   at org.netbeans.modules.parsing.impl.Utilities.runPriorityIO(Utilities.java:90)
   at org.netbeans.modules.parsing.impl.TaskProcessor.runUserTask(TaskProcessor.java:201)
   at org.netbeans.modules.parsing.api.ParserManager.parse(ParserManager.java:104)
   at org.netbeans.modules.javafx2.editor.FXMLCompletion2$Q.query(FXMLCompletion2.java:129)
   at org.netbeans.spi.editor.completion.support.AsyncCompletionTask.run(AsyncCompletionTask.java:223)
   at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1443)
   at org.netbeans.modules.openide.util.GlobalLookup.execute(GlobalLookup.java:68)
   at org.openide.util.lookup.Lookups.executeWith(Lookups.java:303)
   at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:2058)
Caused: org.openide.util.RequestProcessor$FastItem: task failed due to: java.lang.AssertionError