Nullpointer exception for if-else statement having an empty THEN block

[ccjernigan]

I made a typo in a multiline if else statement. While technically valid Kotlin code, it causes Ktlint to crash.

Expected Behavior

I don't know exactly how Ktlint should behave here with regards to formatting, but it probably shouldn't crash.

Observed Behavior

Internal Error (rule 'standard:multiline-if-else') in Test.kt at position '0:0. Please create a ticket at https://github.com/pinterest/ktlint/issues and provide the source code that triggered an error.
com.pinterest.ktlint.rule.engine.api.KtLintRuleException: Rule 'standard:multiline-if-else' throws exception in file 'PrepareGoogle.kt' at position (0:0)
   Rule maintainer: KtLint
   Issue tracker  : https://github.com/pinterest/ktlint/issues
   Repository     : https://github.com/pinterest/ktlint
	at com.pinterest.ktlint.rule.engine.internal.RuleExecutionContext.executeRule(RuleExecutionContext.kt:65)
	at com.pinterest.ktlint.rule.engine.api.KtLintRuleEngine$format$3.invoke(KtLintRuleEngine.kt:154)
	at com.pinterest.ktlint.rule.engine.api.KtLintRuleEngine$format$3.invoke(KtLintRuleEngine.kt:153)
	at com.pinterest.ktlint.rule.engine.internal.VisitorProvider$visitor$3.invoke(VisitorProvider.kt:46)
	at com.pinterest.ktlint.rule.engine.internal.VisitorProvider$visitor$3.invoke(VisitorProvider.kt:44)
	at com.pinterest.ktlint.rule.engine.api.KtLintRuleEngine.format(KtLintRuleEngine.kt:153)
	at com.pinterest.ktlint.cli.internal.KtlintCommandLine.format(KtlintCommandLine.kt:485)
	at com.pinterest.ktlint.cli.internal.KtlintCommandLine.process(KtlintCommandLine.kt:471)
	at com.pinterest.ktlint.cli.internal.KtlintCommandLine.access$process(KtlintCommandLine.kt:61)
	at com.pinterest.ktlint.cli.internal.KtlintCommandLine$lintFiles$3.invoke$lambda$0(KtlintCommandLine.kt:411)
	at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
	at java.base/java.lang.Thread.run(Thread.java:833)
Caused by: java.lang.NullPointerException: Cannot invoke "org.jetbrains.kotlin.com.intellij.lang.ASTNode.getElementType()" because the return value of "org.jetbrains.kotlin.com.intellij.lang.ASTNode.getFirstChildNode()" is null
	at com.pinterest.ktlint.ruleset.standard.rules.MultiLineIfElseRule.beforeVisitChildNodes(MultiLineIfElseRule.kt:98)
	at com.pinterest.ktlint.rule.engine.internal.RuleExecutionContext$executeRuleOnNodeRecursively$1.invoke(RuleExecutionContext.kt:125)
	at com.pinterest.ktlint.rule.engine.internal.RuleExecutionContext$executeRuleOnNodeRecursively$1.invoke(RuleExecutionContext.kt:124)
	at com.pinterest.ktlint.rule.engine.internal.SuppressHandler.handle(SuppressHandler.kt:28)
	at com.pinterest.ktlint.rule.engine.internal.RuleExecutionContext.executeRuleOnNodeRecursively(RuleExecutionContext.kt:124)
	at com.pinterest.ktlint.rule.engine.internal.RuleExecutionContext.executeRuleOnNodeRecursively(RuleExecutionContext.kt:93)
	at com.pinterest.ktlint.rule.engine.internal.RuleExecutionContext.access$executeRuleOnNodeRecursively(RuleExecutionContext.kt:30)
	at com.pinterest.ktlint.rule.engine.internal.RuleExecutionContext$executeRuleOnNodeRecursively$2$1.invoke(RuleExecutionContext.kt:132)
	at com.pinterest.ktlint.rule.engine.internal.RuleExecutionContext$executeRuleOnNodeRecursively$2$1.invoke(RuleExecutionContext.kt:131)
	at com.pinterest.ktlint.rule.engine.internal.SuppressHandler.handle(SuppressHandler.kt:28)
	at com.pinterest.ktlint.rule.engine.internal.RuleExecutionContext.executeRuleOnNodeRecursively(RuleExecutionContext.kt:131)
	at com.pinterest.ktlint.rule.engine.internal.RuleExecutionContext.executeRuleOnNodeRecursively(RuleExecutionContext.kt:93)
	at com.pinterest.ktlint.rule.engine.internal.RuleExecutionContext.access$executeRuleOnNodeRecursively(RuleExecutionContext.kt:30)
	at com.pinterest.ktlint.rule.engine.internal.RuleExecutionContext$executeRuleOnNodeRecursively$2$1.invoke(RuleExecutionContext.kt:132)
	at com.pinterest.ktlint.rule.engine.internal.RuleExecutionContext$executeRuleOnNodeRecursively$2$1.invoke(RuleExecutionContext.kt:131)
	at com.pinterest.ktlint.rule.engine.internal.SuppressHandler.handle(SuppressHandler.kt:28)
	at com.pinterest.ktlint.rule.engine.internal.RuleExecutionContext.executeRuleOnNodeRecursively(RuleExecutionContext.kt:131)
	at com.pinterest.ktlint.rule.engine.internal.RuleExecutionContext.executeRuleOnNodeRecursively(RuleExecutionContext.kt:93)
	at com.pinterest.ktlint.rule.engine.internal.RuleExecutionContext.access$executeRuleOnNodeRecursively(RuleExecutionContext.kt:30)
	at com.pinterest.ktlint.rule.engine.internal.RuleExecutionContext$executeRuleOnNodeRecursively$2$1.invoke(RuleExecutionContext.kt:132)
	at com.pinterest.ktlint.rule.engine.internal.RuleExecutionContext$executeRuleOnNodeRecursively$2$1.invoke(RuleExecutionContext.kt:131)
	at com.pinterest.ktlint.rule.engine.internal.SuppressHandler.handle(SuppressHandler.kt:28)
	at com.pinterest.ktlint.rule.engine.internal.RuleExecutionContext.executeRuleOnNodeRecursively(RuleExecutionContext.kt:131)
	at com.pinterest.ktlint.rule.engine.internal.RuleExecutionContext.executeRuleOnNodeRecursively(RuleExecutionContext.kt:93)
	at com.pinterest.ktlint.rule.engine.internal.RuleExecutionContext.access$executeRuleOnNodeRecursively(RuleExecutionContext.kt:30)
	at com.pinterest.ktlint.rule.engine.internal.RuleExecutionContext$executeRuleOnNodeRecursively$2$1.invoke(RuleExecutionContext.kt:132)
	at com.pinterest.ktlint.rule.engine.internal.RuleExecutionContext$executeRuleOnNodeRecursively$2$1.invoke(RuleExecutionContext.kt:131)
	at com.pinterest.ktlint.rule.engine.internal.SuppressHandler.handle(SuppressHandler.kt:28)
	at com.pinterest.ktlint.rule.engine.internal.RuleExecutionContext.executeRuleOnNodeRecursively(RuleExecutionContext.kt:131)
	at com.pinterest.ktlint.rule.engine.internal.RuleExecutionContext.executeRuleOnNodeRecursively(RuleExecutionContext.kt:93)
	at com.pinterest.ktlint.rule.engine.internal.RuleExecutionContext.access$executeRuleOnNodeRecursively(RuleExecutionContext.kt:30)
	at com.pinterest.ktlint.rule.engine.internal.RuleExecutionContext$executeRuleOnNodeRecursively$2$1.invoke(RuleExecutionContext.kt:132)
	at com.pinterest.ktlint.rule.engine.internal.RuleExecutionContext$executeRuleOnNodeRecursively$2$1.invoke(RuleExecutionContext.kt:131)
	at com.pinterest.ktlint.rule.engine.internal.SuppressHandler.handle(SuppressHandler.kt:28)
	at com.pinterest.ktlint.rule.engine.internal.RuleExecutionContext.executeRuleOnNodeRecursively(RuleExecutionContext.kt:131)
	at com.pinterest.ktlint.rule.engine.internal.RuleExecutionContext.executeRuleOnNodeRecursively(RuleExecutionContext.kt:93)
	at com.pinterest.ktlint.rule.engine.internal.RuleExecutionContext.access$executeRuleOnNodeRecursively(RuleExecutionContext.kt:30)
	at com.pinterest.ktlint.rule.engine.internal.RuleExecutionContext$executeRuleOnNodeRecursively$2$1.invoke(RuleExecutionContext.kt:132)
	at com.pinterest.ktlint.rule.engine.internal.RuleExecutionContext$executeRuleOnNodeRecursively$2$1.invoke(RuleExecutionContext.kt:131)
	at com.pinterest.ktlint.rule.engine.internal.SuppressHandler.handle(SuppressHandler.kt:28)
	at com.pinterest.ktlint.rule.engine.internal.RuleExecutionContext.executeRuleOnNodeRecursively(RuleExecutionContext.kt:131)
	at com.pinterest.ktlint.rule.engine.internal.RuleExecutionContext.executeRuleOnNodeRecursively(RuleExecutionContext.kt:93)
	at com.pinterest.ktlint.rule.engine.internal.RuleExecutionContext.access$executeRuleOnNodeRecursively(RuleExecutionContext.kt:30)

Steps to Reproduce

    if ("a" == "b") {
    } else if ("b" == "c") else {
    }

Your Environment

• Version of ktlint used: 0.50.0
• Relevant parts of the .editorconfig settings
• Name and version (or code for custom task) of integration used (Gradle plugin, Maven plugin, command line, custom Gradle task): Custom Gradle task
• Version of Gradle used (if applicable): 8.2.1
• Operating System and version: macOS

[paul-dingemans]

    if ("a" == "b") {
    } else if ("b" == "c") else {
    }

Kotlin keeps amazing me. I would never have expected that this was valid Kotlin code. Tnx for reporting the bug.