NullPointerException in IJ error dialog

[Vampire]

java.lang.NullPointerException
	at java.lang.String.compareTo(String.java:1155)
	at org.codinjutsu.tools.mongo.view.model.MongoTreeBuilder.lambda$new$43(MongoTreeBuilder.java:61)
	at com.intellij.ide.util.treeView.AbstractTreeUi$1.compare(AbstractTreeUi.java:75)
	at com.intellij.ide.util.treeView.AbstractTreeUi$1.compare(AbstractTreeUi.java:60)
	at java.util.TimSort.countRunAndMakeAscending(TimSort.java:355)
	at java.util.TimSort.sort(TimSort.java:220)
	at java.util.Arrays.sort(Arrays.java:1512)
	at java.util.ArrayList.sort(ArrayList.java:1456)
	at java.util.Collections.sort(Collections.java:175)
	at com.intellij.ide.util.treeView.AbstractTreeBuilder.sortChildren(AbstractTreeBuilder.java:416)
	at com.intellij.ide.util.treeView.AbstractTreeUi.sortChildren(AbstractTreeUi.java:3559)
	at com.intellij.ide.util.treeView.AbstractTreeUi.insertNodesInto(AbstractTreeUi.java:3494)
	at com.intellij.ide.util.treeView.AbstractTreeUi.access$4100(AbstractTreeUi.java:51)
	at com.intellij.ide.util.treeView.AbstractTreeUi$27.lambda$perform$0(AbstractTreeUi.java:1379)
	at com.intellij.openapi.util.AsyncResult.lambda$doWhenDone$1(AsyncResult.java:45)
	at com.intellij.openapi.util.ExecutionCallback.doWhenExecuted(ExecutionCallback.java:100)
	at com.intellij.openapi.util.ActionCallback.doWhenDone(ActionCallback.java:111)
	at com.intellij.openapi.util.AsyncResult.doWhenDone(AsyncResult.java:45)
	at com.intellij.ide.util.treeView.AbstractTreeUi$27.perform(AbstractTreeUi.java:1378)
	at com.intellij.ide.util.treeView.TreeRunnable.run(TreeRunnable.java:23)
	at com.intellij.ide.util.treeView.TreeRunnable$TreeConsumer.accept(TreeRunnable.java:37)
	at org.jetbrains.concurrency.AsyncPromise$onSuccess$whenComplete$1.accept(AsyncPromise.kt:54)
	at org.jetbrains.concurrency.AsyncPromise$onSuccess$whenComplete$1.accept(AsyncPromise.kt:12)
	at java.util.concurrent.CompletableFuture.uniWhenComplete(CompletableFuture.java:760)
	at java.util.concurrent.CompletableFuture.uniWhenCompleteStage(CompletableFuture.java:778)
	at java.util.concurrent.CompletableFuture.whenComplete(CompletableFuture.java:2140)
	at org.jetbrains.concurrency.AsyncPromise.onSuccess(AsyncPromise.kt:51)
	at com.intellij.ide.util.treeView.AbstractTreeUi.updateNodeChildrenNow(AbstractTreeUi.java:1358)
	at com.intellij.ide.util.treeView.AbstractTreeUi.access$3200(AbstractTreeUi.java:51)
	at com.intellij.ide.util.treeView.AbstractTreeUi$24.perform(AbstractTreeUi.java:1259)
	at com.intellij.ide.util.treeView.TreeRunnable.run(TreeRunnable.java:23)
	at com.intellij.ide.util.treeView.TreeRunnable$TreeConsumer.accept(TreeRunnable.java:37)
	at org.jetbrains.concurrency.AsyncPromise$onSuccess$whenComplete$1.accept(AsyncPromise.kt:54)
	at org.jetbrains.concurrency.AsyncPromise$onSuccess$whenComplete$1.accept(AsyncPromise.kt:12)
	at java.util.concurrent.CompletableFuture.uniWhenComplete(CompletableFuture.java:760)
	at java.util.concurrent.CompletableFuture.uniWhenCompleteStage(CompletableFuture.java:778)
	at java.util.concurrent.CompletableFuture.whenComplete(CompletableFuture.java:2140)
	at org.jetbrains.concurrency.AsyncPromise.onSuccess(AsyncPromise.kt:51)
	at com.intellij.ide.util.treeView.AbstractTreeUi.doUpdateChildren(AbstractTreeUi.java:1255)
	at com.intellij.ide.util.treeView.AbstractTreeUi.access$3000(AbstractTreeUi.java:51)
	at com.intellij.ide.util.treeView.AbstractTreeUi$23$1.perform(AbstractTreeUi.java:1158)
	at com.intellij.ide.util.treeView.TreeRunnable.run(TreeRunnable.java:23)
	at com.intellij.ide.util.treeView.AbstractTreeUi.execute(AbstractTreeUi.java:1822)
	at com.intellij.ide.util.treeView.AbstractTreeUi.access$2600(AbstractTreeUi.java:51)
	at com.intellij.ide.util.treeView.AbstractTreeUi$23.perform(AbstractTreeUi.java:1155)
	at com.intellij.ide.util.treeView.TreeRunnable.run(TreeRunnable.java:23)
	at com.intellij.openapi.util.ActionCallback$ExecutedExecutionCallback.doWhenExecuted(ActionCallback.java:177)
	at com.intellij.openapi.util.ActionCallback.doWhenDone(ActionCallback.java:111)
	at com.intellij.ide.util.treeView.AbstractTreeUi.updateNodeChildren(AbstractTreeUi.java:1150)
	at com.intellij.ide.util.treeView.AbstractTreeUi.updateSubtreeNow(AbstractTreeUi.java:1059)
	at com.intellij.ide.util.treeView.AbstractTreeUpdater$2.perform(AbstractTreeUpdater.java:238)
	at com.intellij.ide.util.treeView.TreeRunnable.run(TreeRunnable.java:23)
	at com.intellij.openapi.util.ActionCallback$ExecutedExecutionCallback.doWhenExecuted(ActionCallback.java:177)
	at com.intellij.openapi.util.ActionCallback.doWhenDone(ActionCallback.java:111)
	at com.intellij.ide.util.treeView.AbstractTreeUpdater.performUpdate(AbstractTreeUpdater.java:233)
	at com.intellij.ide.util.treeView.AbstractTreeUpdater$1.run(AbstractTreeUpdater.java:209)
	at com.intellij.util.ui.update.MergingUpdateQueue.execute(MergingUpdateQueue.java:336)
	at com.intellij.util.ui.update.MergingUpdateQueue.execute(MergingUpdateQueue.java:326)
	at com.intellij.util.ui.update.MergingUpdateQueue.lambda$flush$1(MergingUpdateQueue.java:276)
	at com.intellij.util.ui.UIUtil.invokeAndWaitIfNeeded(UIUtil.java:3070)
	at com.intellij.util.ui.update.MergingUpdateQueue.flush(MergingUpdateQueue.java:287)
	at com.intellij.util.ui.update.MergingUpdateQueue.run(MergingUpdateQueue.java:245)
	at com.intellij.util.concurrency.QueueProcessor.runSafely(QueueProcessor.java:232)
	at com.intellij.util.Alarm$Request.runSafely(Alarm.java:356)
	at com.intellij.util.Alarm$Request.run(Alarm.java:343)
	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at com.intellij.util.concurrency.SchedulingWrapper$MyScheduledFutureTask.run(SchedulingWrapper.java:228)
	at com.intellij.openapi.application.impl.LaterInvocator$FlushQueue.doRun(LaterInvocator.java:435)
	at com.intellij.openapi.application.impl.LaterInvocator$FlushQueue.runNextEvent(LaterInvocator.java:419)
	at com.intellij.openapi.application.impl.LaterInvocator$FlushQueue.run(LaterInvocator.java:403)
	at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:311)
	at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:762)
	at java.awt.EventQueue.access$500(EventQueue.java:98)
	at java.awt.EventQueue$3.run(EventQueue.java:715)
	at java.awt.EventQueue$3.run(EventQueue.java:709)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:80)
	at java.awt.EventQueue.dispatchEvent(EventQueue.java:732)
	at com.intellij.ide.IdeEventQueue.defaultDispatchEvent(IdeEventQueue.java:719)
	at com.intellij.ide.IdeEventQueue._dispatchEvent(IdeEventQueue.java:668)
	at com.intellij.ide.IdeEventQueue.dispatchEvent(IdeEventQueue.java:363)
	at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
	at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
	at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
	at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)