java.lang.AssertionError: unexpected type: <none>
        at com.sun.tools.javac.tree.TreeMaker.Type(TreeMaker.java:639)
        at com.sun.tools.javac.comp.Lower.visitEnumDef(Lower.java:2070)
        at com.sun.tools.javac.comp.Lower.visitClassDef(Lower.java:2003)
        at com.sun.tools.javac.tree.JCTree$JCClassDecl.accept(JCTree.java:587)
        at com.sun.tools.javac.tree.TreeTranslator.translate(TreeTranslator.java:58)
        at com.sun.tools.javac.comp.Lower.translate(Lower.java:1916)
        at com.sun.tools.javac.comp.Lower.translate(Lower.java:1936)
        at com.sun.tools.javac.comp.Lower.translateTopLevelClass(Lower.java:3189)
        at com.sun.tools.javac.main.JavaCompiler.desugar(JavaCompiler.java:1309)
        at com.sun.tools.javac.main.JavaCompiler.desugar(JavaCompiler.java:1210)
        at com.sun.tools.javac.api.JavacTaskImpl$3.process(JavacTaskImpl.java:519)
        at com.sun.tools.javac.api.JavacTaskImpl$Filter.run(JavacTaskImpl.java:607)
        at com.sun.tools.javac.api.JavacTaskImpl.generate(JavacTaskImpl.java:522)
        at org.netbeans.modules.java.source.indexing.MultiPassCompileWorker.compile(MultiPassCompileWorker.java:242)
        at org.netbeans.modules.java.source.indexing.JavaCustomIndexer$1$1.run(JavaCustomIndexer.java:154)
        at org.netbeans.modules.java.source.indexing.JavaCustomIndexer$1$1.run(JavaCustomIndexer.java:134)
        at org.netbeans.modules.java.source.tasklist.TaskCache.refreshTransaction(TaskCache.java:470)
        at org.netbeans.modules.java.source.indexing.JavaCustomIndexer$1.run(JavaCustomIndexer.java:134)
        at org.netbeans.modules.java.source.indexing.JavaCustomIndexer$1.run(JavaCustomIndexer.java:132)
        at org.netbeans.modules.java.source.usages.ClassIndexManager.reserveWriteLock(ClassIndexManager.java:113)
        at org.netbeans.modules.java.source.indexing.JavaCustomIndexer.index(JavaCustomIndexer.java:132)
        at org.netbeans.modules.parsing.spi.indexing.Indexable$MyAccessor.index(Indexable.java:165)
        at org.netbeans.modules.parsing.impl.indexing.RepositoryUpdater$Work.index(RepositoryUpdater.java:1194)
        at org.netbeans.modules.parsing.impl.indexing.RepositoryUpdater$FileListWork.getDone(RepositoryUpdater.java:1513)
        at org.netbeans.modules.parsing.impl.indexing.RepositoryUpdater$Work.doTheWork(RepositoryUpdater.java:1397)
        at org.netbeans.modules.parsing.impl.indexing.RepositoryUpdater$Task._run(RepositoryUpdater.java:2476)
        at org.netbeans.modules.parsing.impl.indexing.RepositoryUpdater$Task.run(RepositoryUpdater.java:2432)
        at org.netbeans.modules.parsing.impl.TaskProcessor$CompilationJob.run(TaskProcessor.java:588)
        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 java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
        at java.lang.Thread.run(Thread.java:619)