I got the following NPE when opening a valid drawing. It opened just fine despite the error.
java.lang.NullPointerException
at de.docs_as_co.intellij.plugin.drawio.utils.LoadableJCEFHtmlPanel$1.onLoadStart$lambda$0(LoadableJCEFHtmlPanel.kt:62)
at com.intellij.util.Alarm$Request.lambda$runSafely$0(Alarm.java:371)
at com.intellij.util.concurrency.ChildContext$runAsCoroutine$1.invoke(propagation.kt:92)
at com.intellij.util.concurrency.ChildContext$runAsCoroutine$1.invoke(propagation.kt:92)
at com.intellij.util.concurrency.ChildContext.runAsCoroutine(propagation.kt:97)
at com.intellij.util.concurrency.ChildContext.runAsCoroutine(propagation.kt:92)
at com.intellij.util.Alarm$Request.lambda$runSafely$1(Alarm.java:369)
at com.intellij.util.concurrency.QueueProcessor.runSafely(QueueProcessor.java:255)
at com.intellij.util.Alarm$Request.runSafely(Alarm.java:368)
at com.intellij.util.Alarm$Request.run(Alarm.java:356)
at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:572)
at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:317)
at com.intellij.util.concurrency.SchedulingWrapper$MyScheduledFutureTask.run(SchedulingWrapper.java:272)
at com.intellij.openapi.application.TransactionGuardImpl.runWithWritingAllowed(TransactionGuardImpl.java:229)
at com.intellij.openapi.application.TransactionGuardImpl.access$100(TransactionGuardImpl.java:22)
at com.intellij.openapi.application.TransactionGuardImpl$1.run(TransactionGuardImpl.java:191)
at com.intellij.openapi.application.impl.AnyThreadWriteThreadingSupport.runIntendedWriteActionOnCurrentThread$lambda$1(AnyThreadWriteThreadingSupport.kt:184)
at com.intellij.openapi.application.impl.AnyThreadWriteThreadingSupport.runWriteIntentReadAction(AnyThreadWriteThreadingSupport.kt:84)
at com.intellij.openapi.application.impl.AnyThreadWriteThreadingSupport.runIntendedWriteActionOnCurrentThread(AnyThreadWriteThreadingSupport.kt:183)
at com.intellij.openapi.application.impl.ApplicationImpl.runIntendedWriteActionOnCurrentThread(ApplicationImpl.java:836)
at com.intellij.openapi.application.impl.ApplicationImpl$2.run(ApplicationImpl.java:425)
at com.intellij.openapi.application.impl.AnyThreadWriteThreadingSupport.runWithImplicitRead(AnyThreadWriteThreadingSupport.kt:122)
at com.intellij.openapi.application.impl.ApplicationImpl.runWithImplicitRead(ApplicationImpl.java:1162)
at com.intellij.openapi.application.impl.FlushQueue.doRun(FlushQueue.java:78)
at com.intellij.openapi.application.impl.FlushQueue.runNextEvent(FlushQueue.java:119)
at com.intellij.openapi.application.impl.FlushQueue.flushNow(FlushQueue.java:41)
at java.desktop/java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:318)
at java.desktop/java.awt.EventQueue.dispatchEventImpl(EventQueue.java:781)
at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:728)
at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:722)
at java.base/java.security.AccessController.doPrivileged(AccessController.java:400)
at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:87)
at java.desktop/java.awt.EventQueue.dispatchEvent(EventQueue.java:750)
at com.intellij.ide.IdeEventQueue.defaultDispatchEvent(IdeEventQueue.kt:696)
at com.intellij.ide.IdeEventQueue._dispatchEvent$lambda$16(IdeEventQueue.kt:590)
at com.intellij.openapi.application.impl.AnyThreadWriteThreadingSupport.runWithoutImplicitRead(AnyThreadWriteThreadingSupport.kt:117)
at com.intellij.ide.IdeEventQueue._dispatchEvent(IdeEventQueue.kt:590)
at com.intellij.ide.IdeEventQueue.access$_dispatchEvent(IdeEventQueue.kt:73)
at com.intellij.ide.IdeEventQueue$dispatchEvent$processEventRunnable$1$1$1$1.compute(IdeEventQueue.kt:357)
at com.intellij.ide.IdeEventQueue$dispatchEvent$processEventRunnable$1$1$1$1.compute(IdeEventQueue.kt:356)
at com.intellij.openapi.progress.impl.CoreProgressManager.computePrioritized(CoreProgressManager.java:843)
at com.intellij.ide.IdeEventQueue$dispatchEvent$processEventRunnable$1$1$1.invoke(IdeEventQueue.kt:356)
at com.intellij.ide.IdeEventQueue$dispatchEvent$processEventRunnable$1$1$1.invoke(IdeEventQueue.kt:351)
at com.intellij.ide.IdeEventQueueKt$performActivity$runnableWithWIL$1.invoke$lambda$0(IdeEventQueue.kt:1035)
at com.intellij.openapi.application.WriteIntentReadAction.lambda$run$0(WriteIntentReadAction.java:24)
at com.intellij.openapi.application.impl.AnyThreadWriteThreadingSupport.runWriteIntentReadAction(AnyThreadWriteThreadingSupport.kt:84)
at com.intellij.openapi.application.impl.ApplicationImpl.runWriteIntentReadAction(ApplicationImpl.java:910)
at com.intellij.openapi.application.WriteIntentReadAction.compute(WriteIntentReadAction.java:55)
at com.intellij.openapi.application.WriteIntentReadAction.run(WriteIntentReadAction.java:23)
at com.intellij.ide.IdeEventQueueKt$performActivity$runnableWithWIL$1.invoke(IdeEventQueue.kt:1035)
at com.intellij.ide.IdeEventQueueKt$performActivity$runnableWithWIL$1.invoke(IdeEventQueue.kt:1035)
at com.intellij.ide.IdeEventQueueKt.performActivity$lambda$1(IdeEventQueue.kt:1036)
at com.intellij.openapi.application.TransactionGuardImpl.performActivity(TransactionGuardImpl.java:106)
at com.intellij.ide.IdeEventQueueKt.performActivity(IdeEventQueue.kt:1036)
at com.intellij.ide.IdeEventQueue.dispatchEvent$lambda$10(IdeEventQueue.kt:351)
at com.intellij.ide.IdeEventQueue.dispatchEvent(IdeEventQueue.kt:397)
at java.desktop/java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:207)
at java.desktop/java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:128)
at java.desktop/java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:117)
at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:113)
at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:105)
at java.desktop/java.awt.EventDispatchThread.run(EventDispatchThread.java:92)
I got the following NPE when opening a valid drawing. It opened just fine despite the error.