简单粗暴的解决方法：
（1）进入项目路径>.idea
（2）找到 mongoSettings.xml ，删掉
（3）重新打开项目目录，重新创建链接，成功链接并展示
tips:
目前这个问题应该没有完全解决，作者发布了多个插件，目前依然不断有该错误日志上报。
报错信息：
org.codinjutsu.tools.mongo.view.model.MongoTreeBuilder
java.lang.NullPointerException
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:469)
at com.intellij.ide.util.treeView.AbstractTreeUi.sortChildren(AbstractTreeUi.java:3629)
at com.intellij.ide.util.treeView.AbstractTreeUi.insertNodesInto(AbstractTreeUi.java:3559)
at com.intellij.ide.util.treeView.AbstractTreeUi.access$4100(AbstractTreeUi.java:51)
at com.intellij.ide.util.treeView.AbstractTreeUi$29.lambda$perform$0(AbstractTreeUi.java:1386)
at com.intellij.openapi.util.AsyncResult.lambda$doWhenDone$1(AsyncResult.java:46)
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:46)
at com.intellij.ide.util.treeView.AbstractTreeUi$29.perform(AbstractTreeUi.java:1385)
at com.intellij.ide.util.treeView.TreeRunnable.run(TreeRunnable.java:23)
at com.intellij.ide.util.treeView.TreeRunnable$TreeConsumer.accept(TreeRunnable.java:37)
at org.jetbrains.concurrency.DonePromise.onSuccess(DonePromise.java:32)
at com.intellij.ide.util.treeView.AbstractTreeUi.updateNodeChildrenNow(AbstractTreeUi.java:1365)
at com.intellij.ide.util.treeView.AbstractTreeUi.access$3200(AbstractTreeUi.java:51)
at com.intellij.ide.util.treeView.AbstractTreeUi$26.perform(AbstractTreeUi.java:1266)
at com.intellij.ide.util.treeView.TreeRunnable.run(TreeRunnable.java:23)
at com.intellij.ide.util.treeView.TreeRunnable$TreeConsumer.accept(TreeRunnable.java:37)
at org.jetbrains.concurrency.AsyncPromise.callConsumerIfTargeted(AsyncPromise.kt:229)
at org.jetbrains.concurrency.AsyncPromise.setHandler(AsyncPromise.kt:181)
at org.jetbrains.concurrency.AsyncPromise.onSuccess(AsyncPromise.kt:26)
at com.intellij.ide.util.treeView.AbstractTreeUi.doUpdateChildren(AbstractTreeUi.java:1262)
at com.intellij.ide.util.treeView.AbstractTreeUi.access$3000(AbstractTreeUi.java:51)
at com.intellij.ide.util.treeView.AbstractTreeUi$25$1.perform(AbstractTreeUi.java:1165)
at com.intellij.ide.util.treeView.TreeRunnable.run(TreeRunnable.java:23)
at com.intellij.ide.util.treeView.AbstractTreeUi.execute(AbstractTreeUi.java:1848)
at com.intellij.ide.util.treeView.AbstractTreeUi.access$2600(AbstractTreeUi.java:51)
at com.intellij.ide.util.treeView.AbstractTreeUi$25.perform(AbstractTreeUi.java:1162)
at com.intellij.ide.util.treeView.TreeRunnable.run(TreeRunnable.java:23)
at com.intellij.openapi.util.ActionCallback$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:1157)
at com.intellij.ide.util.treeView.AbstractTreeUi.updateSubtreeNow(AbstractTreeUi.java:1061)
at com.intellij.ide.util.treeView.AbstractTreeUpdater$3.perform(AbstractTreeUpdater.java:262)
at com.intellij.ide.util.treeView.TreeRunnable.run(TreeRunnable.java:23)
at com.intellij.openapi.util.ActionCallback$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:257)
at com.intellij.ide.util.treeView.AbstractTreeUpdater$2.run(AbstractTreeUpdater.java:218)
at com.intellij.util.ui.update.MergingUpdateQueue.execute(MergingUpdateQueue.java:337)
at com.intellij.util.ui.update.MergingUpdateQueue.execute(MergingUpdateQueue.java:327)
at com.intellij.util.ui.update.MergingUpdateQueue.lambda$flush$1(MergingUpdateQueue.java:277)
at com.intellij.util.ui.UIUtil.invokeAndWaitIfNeeded(UIUtil.java:3099)
at com.intellij.util.ui.update.MergingUpdateQueue.flush(MergingUpdateQueue.java:288)
at com.intellij.util.ui.update.MergingUpdateQueue.run(MergingUpdateQueue.java:246)
at com.intellij.util.concurrency.QueueProcessor.runSafely(QueueProcessor.java:232)
at com.intellij.util.Alarm$Request.runSafely(Alarm.java:405)
at com.intellij.util.Alarm$Request.access$700(Alarm.java:330)
at com.intellij.util.Alarm$Request$1.run(Alarm.java:371)
at com.intellij.util.Alarm$Request.run(Alarm.java:382)
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 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:781)
at com.intellij.ide.IdeEventQueue._dispatchEvent(IdeEventQueue.java:722)
at com.intellij.ide.IdeEventQueue.dispatchEvent(IdeEventQueue.java:382)
at com.intellij.ide.IdeEventQueue.pumpEventsForHierarchy(IdeEventQueue.java:864)
at com.intellij.openapi.progress.util.ProgressWindow.startBlocking(ProgressWindow.java:205)
at com.intellij.openapi.progress.util.ProgressWindow.startBlocking(ProgressWindow.java:191)
at com.intellij.openapi.application.impl.ApplicationImpl.runProcessWithProgressSynchronously(ApplicationImpl.java:584)
at com.intellij.openapi.progress.impl.CoreProgressManager.runProcessWithProgressSynchronously(CoreProgressManager.java:446)
at com.intellij.openapi.progress.impl.ProgressManagerImpl.runProcessWithProgressSynchronously(ProgressManagerImpl.java:109)
at com.intellij.openapi.progress.impl.CoreProgressManager.runProcessWithProgressSynchronously(CoreProgressManager.java:250)
at com.intellij.openapi.progress.impl.CoreProgressManager.runProcessWithProgressSynchronously(CoreProgressManager.java:203)
at com.intellij.openapi.project.impl.ProjectManagerImpl.loadProjectUnderProgress(ProjectManagerImpl.java:439)
at com.intellij.openapi.project.impl.ProjectManagerImpl.openProject(ProjectManagerImpl.java:414)
at com.intellij.platform.PlatformProjectOpenProcessor.doOpenProject(PlatformProjectOpenProcessor.java:245)
at com.intellij.ide.RecentProjectsManagerBase.doOpenProject(RecentProjectsManagerBase.java:579)
at com.intellij.ide.RecentProjectsManagerBase.doReopenLastProject(RecentProjectsManagerBase.java:706)
at com.intellij.ide.RecentProjectsManagerBase$MyAppLifecycleListener.appStarting(RecentProjectsManagerBase.java:748)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at com.intellij.util.messages.impl.MessageBusConnectionImpl.deliverMessage(MessageBusConnectionImpl.java:117)
at com.intellij.util.messages.impl.MessageBusImpl.doPumpMessages(MessageBusImpl.java:426)
at com.intellij.util.messages.impl.MessageBusImpl.pumpWaitingBuses(MessageBusImpl.java:387)
at com.intellij.util.messages.impl.MessageBusImpl.pumpMessages(MessageBusImpl.java:376)
at com.intellij.util.messages.impl.MessageBusImpl.sendMessage(MessageBusImpl.java:357)
at com.intellij.util.messages.impl.MessageBusImpl.access$200(MessageBusImpl.java:43)
at com.intellij.util.messages.impl.MessageBusImpl$2.invoke(MessageBusImpl.java:208)
at com.sun.proxy.$Proxy50.appStarting(Unknown Source)
at com.intellij.idea.IdeaApplication$IdeStarter.lambda$main$1(IdeaApplication.java:371)
at com.intellij.openapi.application.TransactionGuardImpl.runSyncTransaction(TransactionGuardImpl.java:88)
at com.intellij.openapi.application.TransactionGuardImpl.lambda$submitTransaction$1(TransactionGuardImpl.java:111)
at com.intellij.openapi.application.TransactionGuardImpl.submitTransaction(TransactionGuardImpl.java:120)
at com.intellij.openapi.application.TransactionGuard.submitTransaction(TransactionGuard.java:122)
at com.intellij.idea.IdeaApplication$IdeStarter.main(IdeaApplication.java:369)
at com.intellij.idea.IdeaApplication.lambda$run$1(IdeaApplication.java:209)
at com.intellij.openapi.application.TransactionGuardImpl.performUserActivity(TransactionGuardImpl.java:195)
at com.intellij.idea.IdeaApplication.run(IdeaApplication.java:209)
at com.intellij.idea.IdeaApplication.lambda$initApplication$0(IdeaApplication.java:72)
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.dispatchEvent(IdeEventQueue.java:361)
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)
