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.comp.Annotate.queueScanTreeAndTypeAnnotate(Annotate.java:994)
   at com.sun.tools.javac.comp.Attr.visitVarDef(Attr.java:1125)
   at com.sun.tools.javac.tree.JCTree$JCVariableDecl.accept(JCTree.java:926)
   at com.sun.tools.javac.comp.Attr$ResultInfo.attr(Attr.java:494)
   at com.sun.tools.javac.comp.Attr.attribTree(Attr.java:635)
   at com.sun.tools.javac.comp.Attr.attribStat(Attr.java:705)
   at com.sun.tools.javac.comp.Attr.attribStats(Attr.java:729)
   at com.sun.tools.javac.comp.Attr.visitBlock(Attr.java:1211)
   at org.netbeans.lib.nbjavac.services.NBAttr.visitBlock(NBAttr.java:82)
   at com.sun.tools.javac.tree.JCTree$JCBlock.accept(JCTree.java:990)
   at com.sun.tools.javac.comp.Attr$ResultInfo.attr(Attr.java:494)
   at com.sun.tools.javac.comp.Attr.attribTree(Attr.java:635)
   at com.sun.tools.javac.comp.Attr.attribStat(Attr.java:705)
   at com.sun.tools.javac.comp.Attr.attribStatToTree(Attr.java:412)
   at com.sun.tools.javac.api.JavacTaskImpl.attributeTreeTo(JavacTaskImpl.java:774)
   at org.netbeans.api.java.source.TreeUtilities.reattributeTreeTo(TreeUtilities.java:738)
   at org.netbeans.modules.java.completion.BaseTask.getEnvImpl(BaseTask.java:351)
   at org.netbeans.modules.java.completion.BaseTask.getCompletionEnvironment(BaseTask.java:265)
   at org.netbeans.modules.java.completion.JavaCompletionTask.resolve(JavaCompletionTask.java:265)
   at org.netbeans.modules.java.completion.BaseTask.run(BaseTask.java:92)
   at org.netbeans.modules.java.completion.JavaCompletionTask.run(JavaCompletionTask.java:80)
   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$2.call(TaskProcessor.java:201)
   at org.netbeans.modules.masterfs.filebasedfs.utils.FileChangedManager.priorityIO(FileChangedManager.java:176)
   at org.netbeans.modules.masterfs.providers.ProvidedExtensions.priorityIO(ProvidedExtensions.java:360)
   at org.netbeans.modules.parsing.nb.DataObjectEnvFactory.runPriorityIO(DataObjectEnvFactory.java:141)
   at org.netbeans.modules.parsing.impl.Utilities.runPriorityIO(Utilities.java:88)
   at org.netbeans.modules.parsing.impl.TaskProcessor.runUserTask(TaskProcessor.java:201)
   at org.netbeans.modules.parsing.api.ParserManager.parse(ParserManager.java:104)
   at org.netbeans.modules.editor.java.JavaCompletionProvider$JavaCompletionQuery.query(JavaCompletionProvider.java:234)
   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