ErrorProne crashes with ClassCastException on JDK 14

[mdindoffer]

Description of the problem / feature request:

ErrorProne crashes with ClassCastException on JDK 14. Seems a switch case with a ternary operator causes problems.

Stacktrace

error-prone version: 2.4.0
   BugPattern: NullTernary
   Stack Trace:
   java.lang.ClassCastException: class com.sun.tools.javac.tree.JCTree$JCSwitchExpression cannot be cast to class com.sun.source.tree.SwitchTree (com.sun.tools.javac.tree.JCTree$JCSwitchExpression and com.sun.source.tree.SwitchTree are in module jdk.compiler of loader 'app')
	at com.google.errorprone.util.ASTHelpers$TargetTypeVisitor.visitCase(ASTHelpers.java:1509)
	at com.google.errorprone.util.ASTHelpers$TargetTypeVisitor.visitCase(ASTHelpers.java:1467)
	at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCCase.accept(JCTree.java:1298)
	at jdk.compiler/com.sun.source.util.SimpleTreeVisitor.visit(SimpleTreeVisitor.java:80)
	at com.google.errorprone.util.ASTHelpers.targetType(ASTHelpers.java:1426)
	at com.google.errorprone.bugpatterns.NullTernary.matchConditionalExpression(NullTernary.java:46)
	at com.google.errorprone.scanner.ErrorProneScanner.processMatchers(ErrorProneScanner.java:451)
	at com.google.errorprone.scanner.ErrorProneScanner.visitConditionalExpression(ErrorProneScanner.java:580)
	at com.google.errorprone.scanner.ErrorProneScanner.visitConditionalExpression(ErrorProneScanner.java:152)
	at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCConditional.accept(JCTree.java:1468)
	at jdk.compiler/com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:82)
	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:74)
	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:48)
	at jdk.compiler/com.sun.source.util.TreeScanner.scanAndReduce(TreeScanner.java:90)
	at jdk.compiler/com.sun.source.util.TreeScanner.visitCase(TreeScanner.java:361)
	at com.google.errorprone.scanner.ErrorProneScanner.visitCase(ErrorProneScanner.java:536)
	at com.google.errorprone.scanner.ErrorProneScanner.visitCase(ErrorProneScanner.java:152)
	at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCCase.accept(JCTree.java:1298)
	at jdk.compiler/com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:82)
	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:74)
	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:48)
	at jdk.compiler/com.sun.source.util.TreeScanner.scanAndReduce(TreeScanner.java:90)
	at jdk.compiler/com.sun.source.util.TreeScanner.scan(TreeScanner.java:105)
	at jdk.compiler/com.sun.source.util.TreeScanner.scanAndReduce(TreeScanner.java:113)
	at jdk.compiler/com.sun.source.util.TreeScanner.visitSwitchExpression(TreeScanner.java:346)
	at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCSwitchExpression.accept(JCTree.java:1329)
	at jdk.compiler/com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:82)
	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:74)
	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:48)
	at jdk.compiler/com.sun.source.util.TreeScanner.scanAndReduce(TreeScanner.java:90)
	at jdk.compiler/com.sun.source.util.TreeScanner.visitLambdaExpression(TreeScanner.java:576)
	at com.google.errorprone.scanner.ErrorProneScanner.visitLambdaExpression(ErrorProneScanner.java:704)
	at com.google.errorprone.scanner.ErrorProneScanner.visitLambdaExpression(ErrorProneScanner.java:152)
	at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCLambda.accept(JCTree.java:1917)
	at jdk.compiler/com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:82)
	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:74)
	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:48)
	at jdk.compiler/com.sun.source.util.TreeScanner.scan(TreeScanner.java:105)
	at jdk.compiler/com.sun.source.util.TreeScanner.scanAndReduce(TreeScanner.java:113)
	at jdk.compiler/com.sun.source.util.TreeScanner.visitMethodInvocation(TreeScanner.java:526)
	at com.google.errorprone.scanner.ErrorProneScanner.visitMethodInvocation(ErrorProneScanner.java:753)
	at com.google.errorprone.scanner.ErrorProneScanner.visitMethodInvocation(ErrorProneScanner.java:152)
	at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCMethodInvocation.accept(JCTree.java:1752)
	at jdk.compiler/com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:82)
	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:74)
	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:48)
	at jdk.compiler/com.sun.source.util.TreeScanner.visitExpressionStatement(TreeScanner.java:450)
	at com.google.errorprone.scanner.ErrorProneScanner.visitExpressionStatement(ErrorProneScanner.java:635)
	at com.google.errorprone.scanner.ErrorProneScanner.visitExpressionStatement(ErrorProneScanner.java:152)
	at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCExpressionStatement.accept(JCTree.java:1531)
	at jdk.compiler/com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:82)
	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:74)
	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:48)
	at jdk.compiler/com.sun.source.util.TreeScanner.scanAndReduce(TreeScanner.java:90)
	at jdk.compiler/com.sun.source.util.TreeScanner.scan(TreeScanner.java:105)
	at jdk.compiler/com.sun.source.util.TreeScanner.visitBlock(TreeScanner.java:248)
	at com.google.errorprone.scanner.ErrorProneScanner.visitBlock(ErrorProneScanner.java:522)
	at com.google.errorprone.scanner.ErrorProneScanner.visitBlock(ErrorProneScanner.java:152)
	at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCBlock.accept(JCTree.java:1050)
	at jdk.compiler/com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:82)
	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:74)
	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:48)
	at jdk.compiler/com.sun.source.util.TreeScanner.scanAndReduce(TreeScanner.java:90)
	at jdk.compiler/com.sun.source.util.TreeScanner.visitMethod(TreeScanner.java:206)
	at com.google.errorprone.scanner.ErrorProneScanner.visitMethod(ErrorProneScanner.java:742)
	at com.google.errorprone.scanner.ErrorProneScanner.visitMethod(ErrorProneScanner.java:152)
	at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCMethodDecl.accept(JCTree.java:916)
	at jdk.compiler/com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:82)
	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:74)
	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:48)
	at jdk.compiler/com.sun.source.util.TreeScanner.scanAndReduce(TreeScanner.java:90)
	at jdk.compiler/com.sun.source.util.TreeScanner.scan(TreeScanner.java:105)
	at jdk.compiler/com.sun.source.util.TreeScanner.scanAndReduce(TreeScanner.java:113)
	at jdk.compiler/com.sun.source.util.TreeScanner.visitClass(TreeScanner.java:187)
	at com.google.errorprone.scanner.ErrorProneScanner.visitClass(ErrorProneScanner.java:550)
	at com.google.errorprone.scanner.ErrorProneScanner.visitClass(ErrorProneScanner.java:152)
	at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCClassDecl.accept(JCTree.java:823)
	at jdk.compiler/com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:82)
	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:74)
	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:48)
	at jdk.compiler/com.sun.source.util.TreeScanner.scan(TreeScanner.java:105)
	at jdk.compiler/com.sun.source.util.TreeScanner.scanAndReduce(TreeScanner.java:113)
	at jdk.compiler/com.sun.source.util.TreeScanner.visitCompilationUnit(TreeScanner.java:144)
	at com.google.errorprone.scanner.ErrorProneScanner.visitCompilationUnit(ErrorProneScanner.java:562)
	at com.google.errorprone.scanner.ErrorProneScanner.visitCompilationUnit(ErrorProneScanner.java:152)
	at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCCompilationUnit.accept(JCTree.java:603)
	at jdk.compiler/com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:56)
	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:58)
	at com.google.errorprone.scanner.ErrorProneScannerTransformer.apply(ErrorProneScannerTransformer.java:43)
	at com.google.errorprone.ErrorProneAnalyzer.finished(ErrorProneAnalyzer.java:152)
	at jdk.compiler/com.sun.tools.javac.api.MultiTaskListener.finished(MultiTaskListener.java:132)
	at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.flow(JavaCompiler.java:1423)
	at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.flow(JavaCompiler.java:1370)
	at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:959)
	at jdk.compiler/com.sun.tools.javac.api.JavacTaskImpl.lambda$doCall$0(JavacTaskImpl.java:104)
	at jdk.compiler/com.sun.tools.javac.api.JavacTaskImpl.handleExceptions(JavacTaskImpl.java:147)
	at jdk.compiler/com.sun.tools.javac.api.JavacTaskImpl.doCall(JavacTaskImpl.java:100)
	at jdk.compiler/com.sun.tools.javac.api.JavacTaskImpl.call(JavacTaskImpl.java:94)
	at org.jetbrains.jps.javac.JavacMain.compile(JavacMain.java:231)
	at org.jetbrains.jps.incremental.java.JavaBuilder.compileJava(JavaBuilder.java:498)
	at org.jetbrains.jps.incremental.java.JavaBuilder.compile(JavaBuilder.java:350)
	at org.jetbrains.jps.incremental.java.JavaBuilder.doBuild(JavaBuilder.java:274)
	at org.jetbrains.jps.incremental.java.JavaBuilder.build(JavaBuilder.java:228)
	at org.jetbrains.jps.incremental.IncProjectBuilder.runModuleLevelBuilders(IncProjectBuilder.java:1441)
	at org.jetbrains.jps.incremental.IncProjectBuilder.runBuildersForChunk(IncProjectBuilder.java:1100)
	at org.jetbrains.jps.incremental.IncProjectBuilder.buildTargetsChunk(IncProjectBuilder.java:1224)
	at org.jetbrains.jps.incremental.IncProjectBuilder.buildChunkIfAffected(IncProjectBuilder.java:1066)
	at org.jetbrains.jps.incremental.IncProjectBuilder.buildChunks(IncProjectBuilder.java:832)
	at org.jetbrains.jps.incremental.IncProjectBuilder.runBuild(IncProjectBuilder.java:419)
	at org.jetbrains.jps.incremental.IncProjectBuilder.build(IncProjectBuilder.java:183)
	at org.jetbrains.jps.cmdline.BuildRunner.runBuild(BuildRunner.java:132)
	at org.jetbrains.jps.cmdline.BuildSession.runBuild(BuildSession.java:302)
	at org.jetbrains.jps.cmdline.BuildSession.run(BuildSession.java:132)
	at org.jetbrains.jps.cmdline.BuildMain$MyMessageHandler.lambda$channelRead0$0(BuildMain.java:219)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:630)
	at java.base/java.lang.Thread.run(Thread.java:832)

Bugs: what's the simplest, easiest way to reproduce this bug? Please provide a minimal example if possible.

static String doStuff(SomeEnum enumVar) {
	return switch (enumVar) {
		case A -> enumVar.name() != null ? "AAA" : null;
		default -> null;
	};
}

static enum SomeEnum {
	A, B
}

What version of Error Prone are you using?

2.4.0