java.lang.AssertionError: isSubtype 12
   at com.sun.tools.javac.code.Types$5.visitType(Types.java:423)
   at com.sun.tools.javac.code.Types$5.visitType(Types.java:403)
   at com.sun.tools.javac.code.Types$DefaultTypeVisitor.visitMethodType(Types.java:3747)
   at com.sun.tools.javac.code.Type$MethodType.accept(Type.java:886)
   at com.sun.tools.javac.code.Types$DefaultTypeVisitor.visit(Types.java:3743)
   at com.sun.tools.javac.code.Types.isSubtype(Types.java:399)
   at com.sun.tools.javac.code.Types.isSubtypeNoCapture(Types.java:378)
   at com.sun.tools.javac.code.Types$5.visitClassType(Types.java:484)
   at com.sun.tools.javac.code.Types$5.visitClassType(Types.java:403)
   at com.sun.tools.javac.code.Type$ClassType.accept(Type.java:583)
   at com.sun.tools.javac.code.Types$DefaultTypeVisitor.visit(Types.java:3743)
   at com.sun.tools.javac.code.Types.isSubtype(Types.java:399)
   at com.sun.tools.javac.code.Types.isSubtype(Types.java:375)
   at com.sun.tools.javac.model.JavacTypes.isSubtype(JavacTypes.java:93)
   at org.netbeans.modules.editor.java.JavaCompletionProvider$JavaCompletionQuery.asMemberOf(JavaCompletionProvider.java:4633)
   at org.netbeans.modules.editor.java.JavaCompletionProvider$JavaCompletionQuery.addLocalMembersAndVars(JavaCompletionProvider.java:2732)
   at org.netbeans.modules.editor.java.JavaCompletionProvider$JavaCompletionQuery.insideMethodInvocation(JavaCompletionProvider.java:1660)
   at org.netbeans.modules.editor.java.JavaCompletionProvider$JavaCompletionQuery.resolveCompletion(JavaCompletionProvider.java:630)
   at org.netbeans.modules.editor.java.JavaCompletionProvider$JavaCompletionQuery.run(JavaCompletionProvider.java:398)
   at org.netbeans.modules.editor.java.JavaCompletionProvider$JavaCompletionQuery$Task.run(JavaCompletionProvider.java:4951)
   at org.netbeans.modules.parsing.impl.TaskProcessor.callUserTask(TaskProcessor.java:649)
   at org.netbeans.modules.parsing.api.ParserManager$UserTaskAction.run(ParserManager.java:154)
   at org.netbeans.modules.parsing.api.ParserManager$UserTaskAction.run(ParserManager.java:138)
   at org.netbeans.modules.parsing.impl.TaskProcessor$2.call(TaskProcessor.java:217)
   at org.netbeans.modules.parsing.impl.TaskProcessor$2.call(TaskProcessor.java:214)
   at org.netbeans.modules.masterfs.filebasedfs.utils.FileChangedManager.priorityIO(FileChangedManager.java:168)
   at org.netbeans.modules.masterfs.providers.ProvidedExtensions.priorityIO(ProvidedExtensions.java:356)
   at org.netbeans.modules.parsing.impl.Utilities.runPriorityIO(Utilities.java:71)
   at org.netbeans.modules.parsing.impl.TaskProcessor.runUserTask(TaskProcessor.java:214)
   at org.netbeans.modules.parsing.impl.TaskProcessor.runWhenScanFinished(TaskProcessor.java:252)
   at org.netbeans.modules.parsing.api.ParserManager.parseWhenScanFinished(ParserManager.java:131)
   at org.netbeans.modules.editor.java.JavaCompletionProvider$JavaCompletionQuery.query(JavaCompletionProvider.java:290)
   at org.netbeans.spi.editor.completion.support.AsyncCompletionTask.run(AsyncCompletionTask.java:223)
   at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1424)
   at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:1968)
Caused: org.openide.util.RequestProcessor$FastItem: task failed due to: java.lang.AssertionError: isSubtype 12