NPE with IntelliJ 2022.1.1

[electrum]

I had recently opened the IDE and hadn't opened any language files. This happened while the IDE was idle.

java.lang.NullPointerException
	at org.antlr.intellij.plugin.parsing.ParsingUtils.parseText(ParsingUtils.java:206)
	at org.antlr.intellij.plugin.ANTLRv4PluginController.lambda$parseText$3(ANTLRv4PluginController.java:448)
	at com.intellij.openapi.progress.util.BackgroundTaskUtil.lambda$computeInBackgroundAndTryWait$6(BackgroundTaskUtil.java:171)
	at com.intellij.openapi.progress.impl.CoreProgressManager.lambda$runProcess$2(CoreProgressManager.java:189)
	at com.intellij.openapi.progress.impl.CoreProgressManager.lambda$executeProcessUnderProgress$12(CoreProgressManager.java:608)
	at com.intellij.openapi.progress.impl.CoreProgressManager.registerIndicatorAndRun(CoreProgressManager.java:683)
	at com.intellij.openapi.progress.impl.CoreProgressManager.computeUnderProgress(CoreProgressManager.java:639)
	at com.intellij.openapi.progress.impl.CoreProgressManager.executeProcessUnderProgress(CoreProgressManager.java:607)
	at com.intellij.openapi.progress.impl.ProgressManagerImpl.executeProcessUnderProgress(ProgressManagerImpl.java:60)
	at com.intellij.openapi.progress.impl.CoreProgressManager.runProcess(CoreProgressManager.java:176)
	at com.intellij.openapi.progress.util.BackgroundTaskUtil.lambda$computeInBackgroundAndTryWait$7(BackgroundTaskUtil.java:170)
	at com.intellij.openapi.application.impl.ApplicationImpl$1.run(ApplicationImpl.java:295)
	at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
	at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
	at java.base/java.util.concurrent.Executors$PrivilegedThreadFactory$1$1.run(Executors.java:668)
	at java.base/java.util.concurrent.Executors$PrivilegedThreadFactory$1$1.run(Executors.java:665)
	at java.base/java.security.AccessController.doPrivileged(Native Method)
	at java.base/java.util.concurrent.Executors$PrivilegedThreadFactory$1.run(Executors.java:665)
	at java.base/java.lang.Thread.run(Thread.java:829)

[parrt]

Wow! Latest version 1.19.2?

[electrum]

IntelliJ said all plugins were up to date. I’ll manually confirm the plugin version next time I’m at the office.

[parrt]

Ok, thanks. So literally there were no .g4 files open the last time you had intellij open? I think it is executing code that can only happen when there's a grammar file. It looks to me like we are passing in a null lexer (lg):

previewState.parsingResult = ParsingUtils.parseText(
	previewState.g, previewState.lg, previewState.startRuleName,
	grammarFile, inputText, project
);

which then tries to parse:

lexEngine = lg.createLexerInterpreter(input);

This does seem to be an unprotected "missing or bad lexer" situation but I'm wondering why it doesn't come up before. Maybe you could find the log file in the help menu and attach it here or email it to me?

[kspalaiologos]

I get the same stacktrace:

java.lang.NullPointerException
	at org.antlr.intellij.plugin.parsing.ParsingUtils.parseText(ParsingUtils.java:206)
	at org.antlr.intellij.plugin.ANTLRv4PluginController.lambda$parseText$3(ANTLRv4PluginController.java:448)
	at com.intellij.openapi.progress.util.BackgroundTaskUtil.lambda$computeInBackgroundAndTryWait$6(BackgroundTaskUtil.java:171)
	at com.intellij.openapi.progress.impl.CoreProgressManager.lambda$runProcess$2(CoreProgressManager.java:189)
	at com.intellij.openapi.progress.impl.CoreProgressManager.lambda$executeProcessUnderProgress$12(CoreProgressManager.java:608)
	at com.intellij.openapi.progress.impl.CoreProgressManager.registerIndicatorAndRun(CoreProgressManager.java:683)
	at com.intellij.openapi.progress.impl.CoreProgressManager.computeUnderProgress(CoreProgressManager.java:639)
	at com.intellij.openapi.progress.impl.CoreProgressManager.executeProcessUnderProgress(CoreProgressManager.java:607)
	at com.intellij.openapi.progress.impl.ProgressManagerImpl.executeProcessUnderProgress(ProgressManagerImpl.java:60)
	at com.intellij.openapi.progress.impl.CoreProgressManager.runProcess(CoreProgressManager.java:176)
	at com.intellij.openapi.progress.util.BackgroundTaskUtil.lambda$computeInBackgroundAndTryWait$7(BackgroundTaskUtil.java:170)
	at com.intellij.openapi.application.impl.ApplicationImpl$1.run(ApplicationImpl.java:295)
	at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
	at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
	at java.base/java.util.concurrent.Executors$PrivilegedThreadFactory$1$1.run(Executors.java:668)
	at java.base/java.util.concurrent.Executors$PrivilegedThreadFactory$1$1.run(Executors.java:665)
	at java.base/java.security.AccessController.doPrivileged(Native Method)
	at java.base/java.util.concurrent.Executors$PrivilegedThreadFactory$1.run(Executors.java:665)
	at java.base/java.lang.Thread.run(Thread.java:829)

It happened shortly after I closed the .g4 file.

[parrt]

Is there a specific process you could identify that causes it fairly reliable? Another words can you start up your IDE, Open that file then close it and get the error? Thanks very much for Stack trace! Could you post your grammar as well if it's not private? Happy to get log files too.

[electrum]

For me this happened with https://github.com/trinodb/trino

[ktr62]

Seen with 2022.1.3 and all plugins up to date as well. Not quite sure, if there was a g4 file open or not. Just started IJ with a project opened and closed a bunch of files, then saw the event log entry with this same back trace, Still drilling down a bit...

[bjansen]

The preview input is now parsed in a background thread, so it's theoretically possible to close the editor before the scheduled bg thread is executed. In this case, editorFileClosedEvent will clear both previewState.g and previewState.lg, causing a NPE in the bg thread.