Structure view shows "loading ..." but nothing comes up

[fpga-guy]

I was able to bring up the structure view on my grammar once. The next time I opened the IDEA editor it failed with the following message:

2023-09-01 10:51:15,454 [   7535] SEVERE - #c.i.u.c.Invoker - String index out of range: 0
java.lang.StringIndexOutOfBoundsException: String index out of range: 0
	at java.base/java.lang.StringLatin1.charAt(StringLatin1.java:48)
	at java.base/java.lang.String.charAt(String.java:1517)
	at org.antlr.intellij.plugin.structview.ANTLRv4StructureViewModel$1.lambda$getComparator$0(ANTLRv4StructureViewModel.java:30)
	at com.intellij.ide.util.treeView.smartTree.CachingChildrenTreeNode$CompositeComparator.compare(CachingChildrenTreeNode.java:79)
	at com.intellij.ide.util.treeView.smartTree.CachingChildrenTreeNode$CompositeComparator.compare(CachingChildrenTreeNode.java:67)
	at java.base/java.util.TimSort.countRunAndMakeAscending(TimSort.java:355)
	at java.base/java.util.TimSort.sort(TimSort.java:234)
	at java.base/java.util.Arrays.sort(Arrays.java:1307)
	at java.base/java.util.ArrayList.sort(ArrayList.java:1721)
	at com.intellij.ide.util.treeView.smartTree.CachingChildrenTreeNode.sortChildren(CachingChildrenTreeNode.java:91)
	at com.intellij.ide.util.treeView.smartTree.TreeElementWrapper.performTreeActions(TreeElementWrapper.java:63)
	at com.intellij.ide.util.treeView.smartTree.CachingChildrenTreeNode.rebuildSubtree(CachingChildrenTreeNode.java:208)
	at com.intellij.ide.util.treeView.smartTree.CachingChildrenTreeNode.ensureChildrenAreInitialized(CachingChildrenTreeNode.java:41)
	at com.intellij.ide.util.treeView.smartTree.CachingChildrenTreeNode.getChildren(CachingChildrenTreeNode.java:33)
	at com.intellij.ide.structureView.newStructureView.StructureViewComponent$MyNodeWrapper.getChildren(StructureViewComponent.java:841)
	at com.intellij.ide.util.treeView.smartTree.SmartTreeStructure.getChildElements(SmartTreeStructure.java:62)
	at com.intellij.ui.tree.StructureTreeModel.getValidChildren(StructureTreeModel.java:411)
	at com.intellij.ui.tree.StructureTreeModel.validateChildren(StructureTreeModel.java:329)
	at com.intellij.ui.tree.StructureTreeModel.getNode(StructureTreeModel.java:323)
	at com.intellij.ui.tree.StructureTreeModel.getChildren(StructureTreeModel.java:343)
	at com.intellij.ui.tree.AsyncTreeModel$CmdGetChildren.getNode(AsyncTreeModel.java:568)
	at com.intellij.ui.tree.AsyncTreeModel$Command.get(AsyncTreeModel.java:464)
	at com.intellij.ui.tree.AsyncTreeModel$Command.get(AsyncTreeModel.java:430)
	at com.intellij.util.concurrency.Invoker$Task.run(Invoker.java:306)
	at com.intellij.openapi.application.impl.ApplicationImpl.tryRunReadAction(ApplicationImpl.java:1133)
	at com.intellij.openapi.progress.util.ProgressIndicatorUtils.lambda$runInReadActionWithWriteActionPriority$0(ProgressIndicatorUtils.java:76)
	at com.intellij.openapi.progress.util.ProgressIndicatorUtilService.runActionAndCancelBeforeWrite(ProgressIndicatorUtilService.java:63)
	at com.intellij.openapi.progress.util.ProgressIndicatorUtils.runActionAndCancelBeforeWrite(ProgressIndicatorUtils.java:133)
	at com.intellij.openapi.progress.util.ProgressIndicatorUtils.lambda$runWithWriteActionPriority$1(ProgressIndicatorUtils.java:114)
	at com.intellij.openapi.progress.ProgressManager.lambda$runProcess$0(ProgressManager.java:71)
	at com.intellij.openapi.progress.impl.CoreProgressManager.lambda$runProcess$2(CoreProgressManager.java:186)
	at com.intellij.openapi.progress.impl.CoreProgressManager.lambda$executeProcessUnderProgress$13(CoreProgressManager.java:604)
	at com.intellij.openapi.progress.impl.CoreProgressManager.registerIndicatorAndRun(CoreProgressManager.java:679)
	at com.intellij.openapi.progress.impl.CoreProgressManager.computeUnderProgress(CoreProgressManager.java:635)
	at com.intellij.openapi.progress.impl.CoreProgressManager.executeProcessUnderProgress(CoreProgressManager.java:603)
	at com.intellij.openapi.progress.impl.ProgressManagerImpl.executeProcessUnderProgress(ProgressManagerImpl.java:61)
	at com.intellij.openapi.progress.impl.CoreProgressManager.runProcess(CoreProgressManager.java:173)
	at com.intellij.openapi.progress.ProgressManager.runProcess(ProgressManager.java:71)
	at com.intellij.openapi.progress.util.ProgressIndicatorUtils.runWithWriteActionPriority(ProgressIndicatorUtils.java:111)
	at com.intellij.openapi.progress.util.ProgressIndicatorUtils.runInReadActionWithWriteActionPriority(ProgressIndicatorUtils.java:76)
	at com.intellij.util.concurrency.Invoker.invokeSafely(Invoker.java:188)
	at com.intellij.util.concurrency.Invoker.lambda$offerSafely$0(Invoker.java:165)
	at com.intellij.util.concurrency.Invoker$Background.lambda$offer$0(Invoker.java:433)
	at com.intellij.util.concurrency.BoundedTaskExecutor.doRun(BoundedTaskExecutor.java:249)
	at com.intellij.util.concurrency.BoundedTaskExecutor.access$200(BoundedTaskExecutor.java:31)
	at com.intellij.util.concurrency.BoundedTaskExecutor$1.executeFirstTaskAndHelpQueue(BoundedTaskExecutor.java:227)
	at com.intellij.util.ConcurrencyUtil.runUnderThreadName(ConcurrencyUtil.java:218)
	at com.intellij.util.concurrency.BoundedTaskExecutor$1.run(BoundedTaskExecutor.java:215)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
	at java.base/java.util.concurrent.Executors$PrivilegedThreadFactory$1$1.run(Executors.java:702)
	at java.base/java.util.concurrent.Executors$PrivilegedThreadFactory$1$1.run(Executors.java:699)
	at java.base/java.security.AccessController.doPrivileged(AccessController.java:399)
	at java.base/java.util.concurrent.Executors$PrivilegedThreadFactory$1.run(Executors.java:699)
	at java.base/java.lang.Thread.run(Thread.java:833)
2023-09-01 10:51:15,459 [   7540] SEVERE - #c.i.u.c.Invoker - IntelliJ IDEA 2023.2.1  Build #IC-232.9559.62
2023-09-01 10:51:15,459 [   7540] SEVERE - #c.i.u.c.Invoker - JDK: 17.0.8; VM: OpenJDK 64-Bit Server VM; Vendor: JetBrains s.r.o.
2023-09-01 10:51:15,459 [   7540] SEVERE - #c.i.u.c.Invoker - OS: Linux
2023-09-01 10:51:15,460 [   7541] SEVERE - #c.i.u.c.Invoker - Plugin to blame: ANTLR v4 version: 1.20

I've tried open/close and the structure still fails to load. As I experiment with possible fixes, I'll update this message.

[fpga-guy]

I deleted the .idea editor configuration directory and re-invoked the application. It created a new project in place. The structure window now displays my .g4 file correctly. I'm not sure what made it get sideways, but this seems to be the solution.

[bjansen]

Looks like a duplicate of #650